Mmm... I tend to just do it locally. It's been 2 years and I've already got fifteen gigs of stuff for animation. A large collection of pixel art as well.
Here's a blog I like:
http://cammadanar.tumblr.com/ It's kind of dead right now, but posts well mades gifs from all sorts of things, mainly from Anime. It's only 205 pages, you could make it through the archive rather quickly.
It'll show you
rotoscopes,
comparisons of stages of production,
mocap (though I'm aware you're interested just in drawn things.There's
this blog which... has apparently changed since I last went there. It used to be exactly what you wanted, except only for effects. You could choose say... fire and it would show you just the fire ones. It may still be searchable, but I couldn't find how to do it with a quick check. Edit: I just really checked it again, this is probably now exactly what you want. And no longer just about effects. Check it out!
The
Animator Expo has been a cool thing to follow so far. Fairly different styles, frame rates, and updated nearly every week. Lots of nudity, most aren't like MeMeMe I promise.
Realizing I've posted a fair amount of Anime stuff, you might enjoy
Catsuka's tumblr. Haven't really browsed there much myself, but knowing what Catsuka is about, you might enjoy it.
AVIdemux is super cool/easy to use if you want to look at a video frame by frame. You may find cool info in short films you already have on your computer.
I'm aware of quite a few places that specialize on production art (that is storyboards, model sheets and the like), but it seems like you're more into seeing things move.
I guess my answer is I've been doing this a long time and haven't really found a cool
single source for EVERYTHING. But I could drop links all day. To specific animators, to more blogs, to whatever. For pixel art, I'm on this website and pixel joint's gallery every day. I download everything good.
I went through 1367 pages of this thread and also downloaded the good stuff. It's... kind of obsessive, but that's how I keep up with this stuff. I too would be interested in any kind of comprehensive database.
Edit: Oh yeah. I can't imagine you haven't seen this, but here's third strike:
http://www.zweifuss.ca/You said you don't like spritesheets. That's every thing in the game timed (mostly properly. 60 FPS and gif don't play well together.), and easy to access.