I never used screensavers very much, none of them really kept me interested for more than a day or two. But for some reason today I suddenly decided to see what's out there.
Right now I'm looking at what ScreensPro has to offer. Not all their savers have the resolution necessary for my 30-inch screen (they tell me current computers don't have the power for so high resolution animation), but some do. So far I like Electric Jellyfish.
And I bought Something Fishy from uselesscreations.com. I like it. See video.
I also like the CafeWall one. (The download is only 16k!)
Update: Comments so far point out that I save the screen and power much more by using sleep instead of a screensaver, which is non-functional with an LCD screen, and is only eye candy. Which is true. I'll only use them when I'm zipping back and forth to the computer all the time.