http://pybonacci.org/2014/01/24/157-cosas-de-ipython-que-no-sabias-y-nunca-preguntaste-i/ (in Spanish)
A magic that let us play with jinja2 by bj0.
http://nbviewer.ipython.org/github/ipython-books/cookbook-code/blob/master/notebooks/chapter01_basic/04_magic.ipynb (it is part of the excellent book "IPython Interactive Computing and Visualization Cookbook" written by Cyrille Rossant and already linked in the previous section).
Some notebook styles by Rob Story
Notebooks about css theming by Matthias Bussonnier: [1] and [2]
More css theming by Henry Hammond
Blog posts by Damián Ávila: [1], [2] and [3]
Notebook extensions by Min Ragan Kelley
Unofficial repository for IPython notebooks extensions
https://github.com/ipython/ipython/wiki/Extensions-Index
Blog post about notebook extensions by Stefan Pfenninger
Cursor blink rate on codemirror
https://blog.safaribooksonline.com/2013/12/18/ipython-notebook-plugins/