www.animewallpapers.com (wallpaper site)
www.anipike.com (used to be the single largest collection of anime-related links this side of the net, not sure if they still navigate all that well)
Lockstock: " i gots the power!" Sweetdeily: "you know he-man was a gay icon, right?" *SILENCE*
http://animepaper.net/ - community based entirely around the anime wallpaper scene. They have a great collection of scans that you can use to make your own wallpapers. They have some of the best anime wallpapers IMO.