In the new version of Ubuntu i.e Ubuntu 10.10 Maverick Meerkat(released few weeks ago),some new and charming wallpapers has been added by default.If you haven’t installed Ubuntu 10.10 yet,then here is some natural wallpaper snapshots and download link for you;that I like.
Wallpaper 1 : Feather
Wallpaper 2 : Comet
Wallpaper 3 : Crocosmia
Download above three wallpapers for your Desktop.