All-4-Free Freebie Tree
   Provides pranks, jokes, and downloadable freebies.
   http://www.all-4-free.com/specials/aprilfools.html

April Fool's Day Prank Software
   Offers free harmless joke and prank software.
   http://www.rjlsoftware.com/software/entertainment/

April Fools Practical Jokes Gag Gifts
   Contains a list of pranks from 1990 to present day. Also includes ideas for gag pranks.
   http://www.april-fools.us/

April Fools on the Net
   An archive of net humor, pranks, jokes and foolishness.
   http://www.2meta.com/april-fools/

April Fools' Special: History's Hoaxes
   National Geographic compilation that includes explanation of how some hoaxes were done, how they were spread, and eventually debunked. Includes definition and history.
   http://news.nationalgeographic.com/news/2003/03/0331_030401_aprilfool.html

Microsoft Buys the Open Directory -- or Not
   Information about 2002 "acquisition" of the ODP by Microsoft. Includes a screen shot of what the main web page looked like.
   http://www.pandia.com/sw-2002/11-god.html

The Kremvax Hoax
   Describes story of how the USSR joined the Internet in 1984. Include original usenet posting and followup. Maintained by the perpetrator himself.
   http://www.godfatherof.nl/kremvax.html

Urgo's list of April Fools' Day Jokes on Websites
   List of annual (since 2004) online pranks on April 1st as submitted by users.
   http://aprilfools.urgo.org/