April Fool's Day: Google

[pseudogeek]

Really Advanced Search: http://www.google.com/js/reallyadvanced.html

There's search by odor there.

Aqua Search: http://www.google.com.hk/intl/zh-CN/landing/shuixia/

Multitask: https://www.google.com/intl/en/chrome/multitask.html

8-Bit Maps: (Just go to Google maps, I don't have a link).

[list incomplete]