1. Where We Do What We Do: A place to view and share pictures of your workplace. Visitors can rate pictures and leave comments. There are some truly great workplaces here. This is where you can get some inspiration to improve your own workspace.
2. TechPosters: Hundreds of poster sized cheatsheets and keyboard shortcuts on various IT topics like programming languages, Linux, software etc, available for download and print. This is a goldmine.
3. FloodMap: A visualization on Google Maps showing the regions of the continents that would get submerged if the ocean level rises, something which is going to happen sooner than you think. The default level is 7 meters but you can choose any level from 0 to 14 meters.
4. Moonbell: The Japanese lunar orbiter Kaguya spent 20 months on the lunar orbit collecting valuable data on the lunar topography. The data from one of the sensors onboard Kaguya called laser altimeter (LALT) is used by this site to generate sounds.
5. How long will IPv4 addresses last? Till 2010, predicts Ars Technia. Internet Doomsday?