Inspired by https://facebook.com/celebratepride - a simple Bash script (30 lines of code) to "prideify" (add rainbow stripes to) any image using ImageMagick.
Only ImageMagick.
./prideify.sh [-r|-b|-p|-t] <input image file>
Output will be at <input image file>-prideified<.extension>
. The optional -r, -b, -p, or -t flags switch between rainbow, bisexual, pansexual, and transgender pride flags, with -r as the default.'
Prideify.js, which does the same thing and much more in JavaScript + Canvas.