If you have a G1 or another Android phone have a look at the excellent free download called WorldTour by BoD.

I've been running this app for a week now with no problems.

This great little app goes online every 30 minutes and grabs a live snapshot from one of hundreds of live web-cams around the world, then sets it as your background wallpaper.

It really makes me want to go travelling asap!

Just search the market place for "worldtour".