This website has been rated number one in the world as far as desktop wallpaper sites go, and for good reasons. The site contains a massive amount of wallpapers and screensavers, all in great quality, in all sizes, and for CPU or mobile phone.
For a little sum, you get to be a member of this community. Benefits include the highest quality material on desktops in the world, MySpace.Com layouts, and even the chance to upload your own artwork. But, if you are not willing to pay for this service, there is a vast section of free wallpapers and all the features standard members get to have, like MySpace layouts and mobile phone screensavers. You might find it interesting because there are a lot of categories to fit every taste. There is an interesting list of links that this site features. From the quality of the site, I can say those may turn out to be excellent websites as well. 
