Open Source Software

• http://sourceforge.net/
• Free desktop software at http://www.openoffice.org/

Astronomy

• Pictures - http://antwrp.gsfc.nasa.gov/apod/astropix.html
• Simulation software http://www.shatters.net/celestia/
  

Tools

• http://www.onlineconversion.com/

Fun & Games

• http://www.websudoku.com/