Programming

HTML5 / JavaScript / WebGL

ICanHaz3D ICanHaz3D – Converts a red/cyan 3D image into 2D. Uses this method from V-Rtifacts.
AverageHash AverageHash - Compares images for similarity. Uses the Average Hash algorithm described by Dr. Neal Krawetz.
DifferenceHash DifferenceHash - My variation of Average Hash, which compares neighbouring areas. Discussed on The Hacker Factor Blog.
Landscape generator 
Landscape generator – Draws a random mountainous landscape against a blue sky. Requires WebGL support.
See Giliam de Carpentier, Hugo Elias, Learning WebGL, WebGL Fundamentals and Song Ho Ahn for code examples and algorithms.
Project Euler 54
Project Euler 84
Project Euler 96
Kaleidoscope Kaleidoscope
Game of life Conway's Game of Life
Absolutely generic game Absolutely generic game with no connection whatsoever to any popular game

CheckiO challenges in JavaScript and Python

See all JavaScript solutions on checkio.org
See all Python solutions on checkio.org

Python

ICanHaz3D implemented with Python and PIL.
AverageHash implemented with Python and PIL.
DifferenceHash implemented with Python and PIL.
Landscape generator implemented with Python, mlab and NumPy.
colournicks.py <Colour nicknames> found in quoted text in HexChat.

Other

jMemorize to Mnemosyne converter – Converts jMemorize flashcards to Mnemosyne.
C♯ version of AverageHash.