SWiSH Max2 ($149.99)
Anime ($49.99) (Seems VERY easy to use; Mac and Windows versions)
Anime Pro ($199.99) (Seems VERY easy to use; Mac and Windows versions)
Express Animator ($39.99)
ToonBoom ($399.99 - $2,999.99 (depending on suite); Free academic licensing) (product used to produce Family Guy, King of the Hill, Spongebob Squarepants, The Simpsons, etc)
KToon (free, no actionscript)
So yeah, those are a few. The more expensive ones are probably not up your alley, but Anime and Anime Pro sound like a good place to look. It's made by the same people who made ArtRage and Poser, so they're pretty reputable. Another interesting product of theirs is
Manga Studio, but that's unrelated. All the same, though, I haven't tried it myself. I'm no good with animation, or at least, I'm not good at it right now. I'm intrigued by Anime, though, since it seems like it has a lot of features that make it easy to get into (skeleton-based animation being a big one).