PhotoJoy – Amazing Photo Widgets, 3D Screensavers & Collages that display your personal photos!
http://www.photojoy.com/index.aspx

interesting

Programma gratuito per Windows in grado di creare collage simpatici e divertenti con le foto, m anche sfondi, screensaver e piccole applicazioni di presentazione

Mac OS Xはスクリーンセーバーが素敵でいいです

Mac screesaver

"Hana is a dream about flowers for computers. The idea is that no aspect of creating the flowers is hidden from the computers, everything is created in code and no bitmaps are used that the computer has not seen to the creation of itself, letting the computer "think" through every step."