electric sheep is an opensource crossplatform screen saver that looks really good. thats right kids. linux/mac/windows.
now i dont lightly say it looks good. i mean some of the renders are amazing and great to stare at. i think it may have been azimov that
wrote a book about those damned electric sheep. something something 
anyway its about your computer dreaming and i think its creating new frames too. anyway check it out.
Electric Sheep Homepage (http://community.electricsheep.org/)