diff --git a/.travis.yml b/.travis.yml
index dd912e73a..59b284b81 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -15,3 +15,4 @@ script:
   - cd test
   - python runtest.py
   - python arrays_test.py
+  - python datasets_test.py
diff --git a/README.md b/README.md
index d340b0d39..bb631349b 100644
--- a/README.md
+++ b/README.md
@@ -3,6 +3,11 @@
 Ray is an experimental distributed execution framework with a Python-like
 programming model. It is under development and not ready for general use.
 
+## Example Code
+
+### Loading ImageNet
+TODO: fill this out.
+
 ## Design Decisions
 
 For a description of our design decisions, see
diff --git a/data/README.md b/data/README.md
new file mode 100644
index 000000000..9f4765b5a
--- /dev/null
+++ b/data/README.md
@@ -0,0 +1,5 @@
+# Data for Ray
+
+This folder contains data neccessary to run tests, etc. Only very small amounts
+of data should be stored here and if a loader for a large dataset is tested, a
+miniature version of this dataset should be created.
diff --git a/data/mini.tar b/data/mini.tar
new file mode 100644
index 000000000..73098dfe5
Binary files /dev/null and b/data/mini.tar differ
diff --git a/examples/imagenet/driver.py b/examples/imagenet/driver.py
new file mode 100644
index 000000000..cc25bfe58
--- /dev/null
+++ b/examples/imagenet/driver.py
@@ -0,0 +1,38 @@
+import argparse
+import boto3
+import os
+import numpy as np
+import ray
+import ray.services as services
+import ray.datasets.imagenet as imagenet
+
+import functions
+
+parser = argparse.ArgumentParser(description="Parse information for data loading.")
+parser.add_argument("--s3-bucket", type=str, help="Name of the bucket that contains the image data.")
+parser.add_argument("--key-prefix", default="ILSVRC2012_img_train/n015", type=str, help="Prefix for files to fetch.")
+parser.add_argument("--drop-ipython", default=False, type=bool, help="Drop into IPython at the end?")
+
+if __name__ == "__main__":
+  args = parser.parse_args()
+  test_path = os.path.join(os.path.dirname(os.path.abspath(__file__)), "worker.py")
+  services.start_singlenode_cluster(return_drivers=False, num_workers_per_objstore=5, worker_path=test_path)
+
+  s3 = boto3.resource("s3")
+  imagenet_bucket = s3.Bucket(args.s3_bucket)
+  objects = imagenet_bucket.objects.filter(Prefix=args.key_prefix)
+  images = [obj.key for obj in objects.all()]
+
+  x = imagenet.load_tarfiles_from_s3(args.s3_bucket, map(str, images), [256, 256]) # TODO(pcm): implement unicode serialization
+
+  mean_image = functions.compute_mean_image(x)
+  mean_image = ray.pull(mean_image)
+
+  print "The mean image is:"
+  print mean_image
+
+  if args.drop_ipython:
+    import IPython
+    IPython.embed()
+
+  services.cleanup()
diff --git a/examples/imagenet/functions.py b/examples/imagenet/functions.py
new file mode 100644
index 000000000..5efe3da7e
--- /dev/null
+++ b/examples/imagenet/functions.py
@@ -0,0 +1,18 @@
+import numpy as np
+from typing import List
+import ray
+import ray.arrays.remote as ra
+
+@ray.remote([List[ray.ObjRef]], [int])
+def num_images(batches):
+  shape_refs = [ra.shape(batch) for batch in batches]
+  return sum([ray.pull(shape_ref)[0] for shape_ref in shape_refs])
+
+@ray.remote([List[ray.ObjRef]], [np.ndarray])
+def compute_mean_image(batches):
+  if len(batches) == 0:
+    raise Exception("No images were passed into `compute_mean_image`.")
+  sum_image_refs = [ra.sum(batch, axis=0) for batch in batches]
+  sum_images = [ray.pull(ref) for ref in sum_image_refs]
+  n_images = num_images(batches)
+  return np.sum(sum_images, axis=0).astype("float64") / ray.pull(n_images)
diff --git a/examples/imagenet/worker.py b/examples/imagenet/worker.py
new file mode 100644
index 000000000..b34c36af1
--- /dev/null
+++ b/examples/imagenet/worker.py
@@ -0,0 +1,33 @@
+import sys
+import argparse
+import numpy as np
+
+import ray.datasets.imagenet
+
+import ray
+import ray.services as services
+import ray.worker as worker
+import ray.arrays.remote as ra
+import ray.arrays.distributed as da
+
+import functions
+
+parser = argparse.ArgumentParser(description="Parse addresses for the worker to connect to.")
+parser.add_argument("--scheduler-address", default="127.0.0.1:10001", type=str, help="the scheduler's address")
+parser.add_argument("--objstore-address", default="127.0.0.1:20001", type=str, help="the objstore's address")
+parser.add_argument("--worker-address", default="127.0.0.1:40001", type=str, help="the worker's address")
+
+if __name__ == "__main__":
+  args = parser.parse_args()
+  worker.connect(args.scheduler_address, args.objstore_address, args.worker_address)
+
+  ray.register_module(ray.datasets.imagenet)
+  ray.register_module(functions)
+  ray.register_module(ra)
+  ray.register_module(ra.random)
+  ray.register_module(ra.linalg)
+  ray.register_module(da)
+  ray.register_module(da.random)
+  ray.register_module(da.linalg)
+
+  worker.main_loop()
diff --git a/lib/python/ray/__init__.py b/lib/python/ray/__init__.py
index 9f8f3132d..182735e35 100644
--- a/lib/python/ray/__init__.py
+++ b/lib/python/ray/__init__.py
@@ -1,3 +1,4 @@
 import libraylib as lib
 import serialization
 from worker import scheduler_info, register_module, connect, disconnect, pull, push, remote
+from libraylib import ObjRef
diff --git a/lib/python/ray/arrays/distributed/linalg.py b/lib/python/ray/arrays/distributed/linalg.py
index 909a1b4d6..257a68da7 100644
--- a/lib/python/ray/arrays/distributed/linalg.py
+++ b/lib/python/ray/arrays/distributed/linalg.py
@@ -176,7 +176,7 @@ def qr(a):
       for r in range(i, a.num_blocks[0]):
         y_ri = y_val.objrefs[r - i, 0]
         W_rcs.append(qr_helper2(y_ri, a_work.objrefs[r, c]))
-      W_c = ra.sum(0, *W_rcs)
+      W_c = ra.linalg.sum_list(*W_rcs)
       for r in range(i, a.num_blocks[0]):
         y_ri = y_val.objrefs[r - i, 0]
         A_rc = qr_helper1(a_work.objrefs[r, c], y_ri, t, W_c)
diff --git a/lib/python/ray/arrays/remote/core.py b/lib/python/ray/arrays/remote/core.py
index c169e7431..65f529c2e 100644
--- a/lib/python/ray/arrays/remote/core.py
+++ b/lib/python/ray/arrays/remote/core.py
@@ -68,9 +68,9 @@ def add(x1, x2):
 def subtract(x1, x2):
   return np.subtract(x1, x2)
 
-@ray.remote([int, np.ndarray], [np.ndarray])
-def sum(axis, *xs):
-  return np.sum(xs, axis=axis)
+@ray.remote([np.ndarray, int], [np.ndarray])
+def sum(x, axis=-1):
+  return np.sum(x, axis=axis if axis != -1 else None)
 
 @ray.remote([np.ndarray], [tuple])
 def shape(a):
diff --git a/lib/python/ray/arrays/remote/linalg.py b/lib/python/ray/arrays/remote/linalg.py
index f79e94684..332394b63 100644
--- a/lib/python/ray/arrays/remote/linalg.py
+++ b/lib/python/ray/arrays/remote/linalg.py
@@ -86,3 +86,7 @@ def matrix_rank(M):
 @ray.remote([np.ndarray], [np.ndarray])
 def multi_dot(*a):
   raise NotImplementedError
+
+@ray.remote([np.ndarray], [np.ndarray])
+def sum_list(*xs):
+  return np.sum(xs, axis=0)
diff --git a/lib/python/ray/datasets/imagenet.py b/lib/python/ray/datasets/imagenet.py
new file mode 100644
index 000000000..a8cd70dbe
--- /dev/null
+++ b/lib/python/ray/datasets/imagenet.py
@@ -0,0 +1,71 @@
+import tarfile, io
+from typing import List
+import PIL.Image
+import numpy as np
+import boto3
+import ray
+
+s3 = boto3.client("s3")
+
+def load_chunk(tarfile, size=None):
+  """Load a number of images from a single imagenet .tar file.
+
+  This function also converts the image from grayscale to RGB if neccessary.
+
+  Args:
+    tarfile (tarfile.TarFile): The archive from which the files get loaded.
+    size (Optional[Tuple[int, int]]): Resize the image to this size if provided.
+
+  Returns:
+    numpy.ndarray: Contains the image data in format [batch, w, h, c]
+  """
+
+  result = []
+  for member in tarfile.getmembers():
+    filename = member.path
+    content = tarfile.extractfile(member)
+    img = PIL.Image.open(content)
+    rgbimg = PIL.Image.new("RGB", img.size)
+    rgbimg.paste(img)
+    if size != None:
+      rgbimg = rgbimg.resize(size, PIL.Image.ANTIALIAS)
+    result.append(np.array(rgbimg).reshape(1, rgbimg.size[0], rgbimg.size[1], 3))
+  return np.concatenate(result)
+
+@ray.remote([str, str, List[int]], [np.ndarray])
+def load_tarfile_from_s3(bucket, s3_key, size=[]):
+  """Load an imagenet .tar file.
+
+  Args:
+    bucket (str): Bucket holding the imagenet .tar.
+    s3_key (str): s3 key from which the .tar file is loaded.
+    size (List[int]): Resize the image to this size if size != []; len(size) == 2 required.
+
+  Returns:
+    np.ndarray: The image data (see load_chunk).
+  """
+
+  response = s3.get_object(Bucket=bucket, Key=s3_key)
+  output = io.BytesIO()
+  chunk = response["Body"].read(1024 * 8)
+  while chunk:
+    output.write(chunk)
+    chunk = response["Body"].read(1024 * 8)
+  output.seek(0) # go to the beginning of the .tar file
+  tar = tarfile.open(mode= "r", fileobj=output)
+  return load_chunk(tar, size=size if size != [] else None)
+
+@ray.remote([str, List[str], List[int]], [List[ray.ObjRef]])
+def load_tarfiles_from_s3(bucket, s3_keys, size=[]):
+  """Load a number of imagenet .tar files.
+
+  Args:
+    bucket (str): Bucket holding the imagenet .tars.
+    s3_keys (List[str]): List of s3 keys from which the .tar files are being loaded.
+    size (List[int]): Resize the image to this size if size != []; len(size) == 2 required.
+
+  Returns:
+    np.ndarray: Contains object references to the chunks of the images (see load_chunk).
+  """
+
+  return [load_tarfile_from_s3(bucket, s3_key, size) for s3_key in s3_keys]
diff --git a/requirements.txt b/requirements.txt
index 6105fd65f..a2bc4a333 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,6 @@
 typing
 funcsigs
 subprocess32
+boto3
+botocore
+Pillow
diff --git a/setup.sh b/setup.sh
index 61bee8917..7bea8cceb 100755
--- a/setup.sh
+++ b/setup.sh
@@ -28,9 +28,9 @@ fi
 
 if [[ $platform == "linux" ]]; then
   sudo apt-get update
-  sudo apt-get install -y git cmake build-essential autoconf libtool python-dev python-numpy python-pip libboost-all-dev unzip
+  sudo apt-get install -y git cmake build-essential autoconf libtool python-dev python-numpy python-pip libboost-all-dev unzip libjpeg8-dev
 elif [[ $platform == "macosx" ]]; then
-  brew install git cmake autoconf libtool boost
+  brew install git cmake autoconf libtool boost libjpeg
   sudo easy_install pip
   sudo pip install numpy
 fi
diff --git a/test/datasets_test.py b/test/datasets_test.py
new file mode 100644
index 000000000..fb0391bbd
--- /dev/null
+++ b/test/datasets_test.py
@@ -0,0 +1,23 @@
+import os
+import tarfile
+import unittest
+import ray
+import ray.services as services
+import ray.datasets.imagenet as imagenet
+
+class ImageNetTest(unittest.TestCase):
+
+  def testImageNetLoading(self):
+    test_dir = os.path.dirname(os.path.abspath(__file__))
+    test_path = os.path.join(test_dir, "test_worker.py")
+    services.start_singlenode_cluster(return_drivers=False, num_workers_per_objstore=5, worker_path=test_path)
+
+    chunk_name = os.path.join(test_dir, "..", "data", "mini.tar")
+    tar = tarfile.open(chunk_name, mode= "r")
+    chunk = imagenet.load_chunk(tar, size=(256, 256))
+    self.assertEqual(chunk.shape, (2, 256, 256, 3))
+
+    services.cleanup()
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/test/test_worker.py b/test/test_worker.py
index 51d5b4ef6..2b02803d0 100644
--- a/test/test_worker.py
+++ b/test/test_worker.py
@@ -5,6 +5,7 @@ import numpy as np
 import test_functions
 import ray.arrays.remote as ra
 import ray.arrays.distributed as da
+import ray.datasets.imagenet
 
 import ray
 import ray.services as services