If you're a fan of Planet Earth (and let's face it, most humans are) then check out the World 400 Theme for Pocket PC.
The theme places a background wallpaper of a vector globe image onto your Windows Mobile device. Unfortunately, it's just an artist's impression rather than a satellite image of our planet, but it does look quite stylish, I guess. The World 400 Theme also darkens the blue menu colors and adds a new transparent Start menu.
If you've ever wanted to hold the World in the palm of your hand then install the World 400 Theme now!