I've never posted anything on DA that I didn't create myself, but I just had to post this screencap taken from "Funeral for a Fiend" (season 19, episode 8). It's a nice shot of Bob's entire family, and Cecil looks so cute here! ^_^
Come to think of it, I believe most of the pictures I'm thinking of were ALL drawn by Ziznine. has some good Simpsons art too, and of course you can find a lot yourself by searching DA for "Cecil Terwilliger," "Sideshow Bob Cecil" or "Simpsons Cecil." I try all three because just searching for "Cecil" is too vague, and you never know which specific search terms to use because all of the above are applicable.