Some of you might enjoy this website:
It's based on that old party game where you pass a whispered message along a line of people and see how humorously garbled it becomes at the end. In this case, a person gives a short description (ie "A webcomic-hosting forum") and the next person has 10 minutes to try and sketch a picture of it, using a very basic on-screen drawing kit. Person #3 then describes the result, and person #4 draws that, and so on. (And yes, the drawing skills on display range from stunningly good to kindergarten-grade bad..) Apart from the often-hilarious results, I'm personally finding it a good test of my improv drawing skills.