I really like images made up of tessellating geometric shapes, so I made a thing which generates wallpaper-sized images made up of triangles.
It renders everything on a
<canvas>, grabbing colours from the ColourLovers API. There are a few customisation options, but the defaults should result in pleasant enough images.
It's available here to have a play with. The source is also available.
The code needs some heavy refactoring, but the project is otherwise feature complete.