Screensavers are a tough bit. On the one hand, they're good for your computer, they save energy, and they provided security. On the other, well, it's tough to find an attractive one. One that's simple, not distracting, and doesn't look like, well, the screen saver that came with your operating system.
But don't set it to black just yet. May I suggest installing one of these awesome, mod clock screen savers?
See, a clock is necessary useful. It's usually graphic, rather than abstract, and it's something you'll not tire of quickly, since, well, it's the time.
I've been using the FLIQLO flip clock for more than a year now, and it's simple and just blends it, but with a bit of style.
See all five (actually six!) at If It's Hip, It's Here