When I'm having a bad drawing day or feeling like my drawing is too stiff and not 'cartoony' enough I like to break out some DVD's or pics I've collected from the web for inspiration. A lot of times I'll watch these old cartoons in slow motion or even frame by frame if a particular movement or expression captures my eye.
I especially love Looney Tunes from the 40's. Bob Clampett's cartoons specifically have some of the wackiest gags and drawings I've ever seen. I especially love scenes that are animated by Rod Scribner.
Thanks to Shane Glines wonderful Cartoon Retro site I've also been exposed to cartoonists like Milton Stein. His comic book work immediately spoke to me. If you don't know who he is, you owe it to yourself to check his work out.
The early Tom & Jerry shorts are awesome too. The other drawings are from the hilarious Tex Avery short 'King Size Canary'. I'm pissed that all his cartoons haven't been released to DVD yet. Luckily I was able to score almost all his MGM shorts via Usenet.