I don't quite know what this is, as I can't read any of the pages, but it has an odd pixie-dust quality. Warning: Don't launch with the sound turned up.
For a fascinating study in spring behavior, or just a fun toy or design tool, check out Springs.
If you don't feel like sitting through the whole movie, try Movie-a-Minute. It and its companion site, Book-a-Minute, are web classics, but Rinkworks (their parent site) has a lot of funny stuff to surf through.
Anyone remember those singing flowers and frogs from a few years back? Here's some horses.
Moon phases, if you're into that kind of thing.
Dreamlines is cool to just sit and watch (I'd imagine it's moreso when under the influence of certain chemicals, not that I'd know anything about that).