Very nice non-apple screensaver!
This is one of the best non-apple screensaver: Fenêtres Volantes! It basically takes the running windows and make them fly around in three-dimension over a black Apple-like background along with the mirror Apple-like effect. It works very well. The only thing I noticed is that it requires a lot of system ressources. I have seen it work on a PowerBook G4 (last model), on a 2.33GHz C2D MBP (256 MB x1600) and on a Quad 2.66 GHz Mac Pro with the x1900 XT. It worked on all but it lagged on the PowerBook, it was better on the MacBook Pro but it still lagged sometimes when it starts and it ran smoothly on the Mac Pro. It still works very well on all these Macs. The built-in Core Animation in Leopard will apparently reduces the strong requirements for this screensaver! Check it out on the developper's site here.