A few of my personal favorites
Iplay
Iplay - a fun, friendly, and free Internet Hangout
NASA
The official site for NASA. Lots of galleries
The Daguerreian Society
The Daguerreian Society
Free Games Online - Your online source for free games on the internet of all kinds!
Lots of Free Games
RadarSat 1
Really cool if you like geology
Virtual Cleeve Abbey, Somerset, England, stunningly recreated by Virtex in three worlds
Some day all websites will look like this! *
Virtual Cultural Center & Museum
My crowning achievement *
* - Requires Viscape SVR