This started as a proof-of-concept, but it turned out to be actually useful.
The idea: Hey, why not have some widgets. They're shiny (at least when properly designed, mine definitely ain't ;-) ), they show useful information, and you have a little more than just a boring wallpaper on your desktop.
However, I'm using a tiling window manager with pseudo-transparent urxvt terminals. I do see my wallpaper, but never my actual desktop. A widget would be totally useless there.
So, I decided to put the widgets directly onto my wallpaper. Each widget is a script producing a PNG image in /tmp, and those are then overlayed onto the wallpaper using ImageMagick. This has some obvious disadvantages (low update frequency, widgets are non-interactive), but besides that, I really like it. I'll not turn this into a project as I'm not sure how many other people find this useful, but for myself I'll definitely keep it.