When I was doing the titlecards for Fanboy, I would receive a workprint of the show to brainstorm concepts off of. The director would pick his favorite and I'd paint it up. Here are a few of my favorite thumbs I did. (Click the Titles to see final versions.)
"The Incredible Chulk"
"Saving Private Chum Chum"
"Battle of the Stands"
I tried to go as fast as I could with these, limiting myself to about an hour to come up with 10 ideas. I enjoyed not worrying about the drawings as much as the idea. Even when I ran out at 7 ideas, I tried really hard to keep going even when i knew it would never fly (ie. Last panel on "Saving Private Chum Chum")
I hope to post some things I've been doing at Ghostbot soon. Stay tuned.