Usually I'm really busy with $work to do, that sometimes, maybe once every 2 months :-) it's just relaxing to take a break and go searching for some new desktop wallpaper.
I can suggest to take a look at our very own wallpapers here on MyOpera. Recently I found out this site that has a nice collection of space pictures, among my favourites.
This incredible picture of Orion is my current wallpaper.
It's taken from this even more incredible site. Caution: don't open it if you need to do something urgent in the next hours :-)