For the last week solid, I've been really digging a thread on the Warren Ellis WHITECHAPEL forum called "The Draw Each Other Art Challenge Thread", where people have been posting cool photos of themselves, and artists have been doing drawings based on those photos.
You can check it out here (Warning: may be NSFW): WHITECHAPEL

It started out slow, but now it's going gangbusters, and it has become a really good art exercise for me; to produce a lot of art, quickly, with good quality, and to heavily use photo-reference and try out lots of new techniques. Good ass-kicker for getting the pixels out and done.
Here's the most recent group of images, more as they accumulate: