My all time favorite screensaver is Johnny Castaway
by Screen Antics.
This was created way long back in 1992 during Windows 3.1 era. I have seen it for the first time in 1997 and I have been using it from windows 95 till window XP.
I am still fascinated with this screensaver and has not seen anything like this till now. Unfortunately this screensaver will not run in Windows 7 x64 as it was made in 16 bit.
I wish someone recreate it again in 3D and similar screensavers for the 64 bit computers.