An idea which has worked well on the Polycount forums (one of the 3D sites I lurk on), which I want to try here. The original thread is here, for the curious; I've taken the liberty of copy/pasting their rules, making only enough changes to make it work for LJ.
1.) You start by posting something old. Original drawings or other original work only; you can't post someone else's work or commercial artwork. Crappy old drawings you're embarassed of now are extremely encouraged! The less finished the better. Doodles and quick sketches preferred. You can post 3 or so drawings at a time.
2.) Once you've posted one of your own drawings, you're free to interpret anything else in the comments. Anything anyone has posted in here, including reinterpretations. The sky's the limit!
3.) You may not post more of your old art (step 1) until you've finished participating yourself (step 2).
4.) When posting images, include a width attribute (I suggest width="90%"), with a link to the full-sized image, to keep people from having to scroll horizontally to see the entire picture.
With that said. . .
Let's see what people can come up with.