Possibly only available today: Homestarrunner.com forgot to pay their domain bill.
The one April Fool's day item that's got everyone confused is the possibility of google.com offering email - in the order of 1GB of storage for each user. It sounds way too good to be true, but it's all over the legit news sites and Googles gone to great lengths to promote this. It's a win-win situation. Either the news sites end up with egg on their face and we get to laugh, or we get a sweet email service that doesn't have anything to do with the borg.
Atari releases the final clip in the 3 part series of promo videos they shot for Driver3. Slick cars, crashes... all the makings of a good video game.