Some experiment with statics files. Clone this in your .ipython/profile_default/static/custom and uncomment the extension you are interested in in custom/custom.js.

This is a simple workaround until we ship IPython with requirejs.

Install

Clone this repo into ~/.ipython_/profile_xxx/static/

git clone https://github.com/ipython-contrib/IPython-notebook-extensions.git ~/.ipython/profile_default/static/custom

Edit ~/.ipython/profile_default/static/custom/custom.js to your preferences. That is to say, uncomment the extensions that interest you.

Restart your notebook server. You may also need to empty your browser cache.

Details

The custom.js file in this branch contains a small load_ext function to help load extensions. Extensions can either be folders named after the extension, containing a main.js script, or a simple Javascript file. You can either load an extension by name if it is in a folder, or by specifying the full path if it ends with .js

IPython-nb-extensions

breakpoint - allow setting of breakpoints for notebook cells
hotkeys - add PGUP / PGDOWN / HOME / END hotkeys for fast scrolling in codecells
slideshow - add toolbar and visual hints to slideshow extension
history - add individual cell history (just a test...)
read-only - allow codecells to be set read-only, so no editing or celle execution is possible
shift-tab - assign shift-tab to dedent
codefolding - fold code blocks using Alt-F or clicking on line numbers
linenumbers - display line numbers in codecells using Alt-N
comment-uncomment - toggle comments in selected lines using Alt-C
split-combine - split/combine cells using Alt-S, Alt-A, Alt-B

The notebook extensions require patching IPython: Add line comment symbol to codemirror-ipython.js:

...
    var external = {
        lineComment: '#', // ** NEW **
        startState: function(basecolumn) {
...

Also, some patching of CodeMirror is required:

Correct CodeMirror.indentRangeFinder in CodeMirror/addon/indent-fold.js (https://github.com/marijnh/CodeMirror/pull/1122)

CodeMirror.indentRangeFinderA = function(cm, start) {
  var tabSize = cm.getOption("tabSize"), firstLine = cm.getLine(start.line);
  var myIndent = CodeMirror.countColumn(firstLine, null, tabSize);
  for (var i = start.line + 1, end = cm.lineCount(); i < end; ++i) {
    var curLine = cm.getLine(i);
    if ((CodeMirror.countColumn(curLine, null, tabSize) == myIndent)&&
          (CodeMirror.countColumn(cm.getLine(i-1), null, tabSize) > myIndent)){
      return {from: {line: start.line, ch: firstLine.length},
              to: {line: i, ch: curLine.length}};
    }
  }
};

Update CodeMirror/addon/fold/foldcolde.js from git repo
Update CodeMirror.defineExtension in CodeMirror/addon/comment/comment.js

  CodeMirror.defineExtension("uncomment", function(from, to, options) {
    if (!options) options = noOptions;
    var self = this, mode = CodeMirror.innerMode(self.getMode(), self.getTokenAt(from).state).mode;
    var end = Math.min(to.line, self.lastLine()), start = Math.min(from.line, end);
    if (to.ch == 0 && to.line > from.line) 
        {
        console.log(start, end);
        end--;
        }
    // Try finding line comments
    var lineString = options.lineComment || mode.lineComment, lines = [];
    var pad = options.padding == null ? " " : options.padding;
    lineComment: for(;;) {
      if (!lineString) break;
      for (var i = start; i <= end; ++i) {
        var line = self.getLine(i);
        var found = line.indexOf(lineString);
        if (found == -1 && (i != end || i == start) && nonWS.test(line)) break lineComment;
        if (i != start && nonWS.test(line.slice(0, found))) break lineComment;
        if (found > 1) break lineComment; // only mind comments at the start of the line
        lines.push(line);
      }