One of the things people ask me about is where do I get my wallpapers. So are are some links to science related sites that provde some really nice wallpapers.
NCAR Weather Photos
The sites has a number of weather related photos including some great lightning pictures.
NOAA Photo Library
A variety of photos from the ocean to space.
Nasa Image Library
Nasa's general image site. Space images along with astronauts and space vehicles.
Nasa JPL Space Images
Want some really cool hard core space images? This is the site for you.