Yea I have had a hard time finding a screen saver site also, though I have found some cool ones that have huge "REGISTER NOW" in the middle of the screen... but they do seem cool.
www.longbowdigitalarts.com, try the protical fire 1/2 screensaver. (If two, configure it, it has this rainbow smoke effect that looks horrid set as default, just use regular smoke, so it's all one color)
yeah i don't bother with a screen saver. Either i turn the monitor off or i just let it go into power save mode. Not much point in screen savers anyway, because monitors now are much better than those that would have an image burned onto them if they were left too long.
I did use the Bink vids of hl2 for a while though. They are good but can cause some problems sometimes.