Since Windows 7's release, Microsoft has been slowly and steadily adding more and more themes to it's personalization gallery.
These themes range from exotic locations, to space, to abstract art, to nature and movies. And these are EXTREMELY high quality theme packs that provided great backgrounds to show off on your large widescreen flat-panel monitors.
Here are some links to a few of the newest themes:
Galapagos
Abstract Diffusion (a favorite of mine)
Classic Managa (Japanese Comics/Animation)
Space Art by GTGraphics
Browse - Download and Enjoy some new background scenery!