This came up as one of the slides in my molecular biology class this past semester. I came across it on the CD that the professor gave us, and if I remember correctly, he said that one of his past students passed it in together with the final saying something to the effect of "I didn't really mean to draw this when I did, but it seemed too cool to toss later." Thought I'd share.
I think my personal favorites are the RNA platyperase and the cracked out TBP.