Animal Splicer 1.0 - This is a silly but fun way to waste some time. It lets you make imaginary creatures by gene splicing.
The Dialectizer- This fun little website will let you translate a website of your choosing into Jive, Redneck, Pig Latin, and more. Very fun.
Virtual Bubble Wrap - Not quite as satifying as the real thing but still fun.
PDFPad.com - This site has a bunch of templates that you can print out including calendars, flags, graph paper, Sudoku, and more!
gethuman 500 database - This is a huge list of customer service numbers with instructions on what keys to press to get through their annoying computer menus so you can speak to a real person.
Zillow.com - This site lets you type in your address and it shows you the estimated value of your home along with the value of the homes around you as well.
Flash Clock: This is just kind of cute and clever if you have not seen it.
Package Tracking: This site allows you to track your UPS, FedEx, USPS, and DHL/AirBorne packages and will even update the results via an RSS feed.
People Clock: This is a clever idea for a clock.