I landed the third piece to my 2001 The Simpsons' Mania! set a while back, and it's perhaps the biggest card in the entire set. Copies routinely go for big bucks and the autograph doesn't appear on eBay very often. Hank Azaria's signature was actually the first I encountered when I lost an auction for it, and it started me in the direction of wanting to complete the set.
So, so beautiful. Azaria's signature surprised me as one of the tougher ones and more expensive pieces of the set, and I'd guess it's at least partially due to the fact that he's had the most crossover success into movies, so he's more recognizable than the other Simpsons' voices. Inkworks went with a great quartet of faces for the front of Hank's card: Chief Wiggum, Apu, Moe, and Frank Grimes (Grimey!).
The back, as always, lists the people portrayed by each voice. Wiggum, Apu, Moe, and Grimey are joined by Comic Book Guy, Kirk Van Houten, and Bumblebee Man.