Steampunk Wallpaper is awesome. I just saw this on Boing Boing.I love the firefox logo with the stitching on it.Check it out.

MacDesktops hosts hundreds of great Hi-Res wallpaper in dozens of Categories. Hours of browsing fun here. I love the My preferences settings to show you just the sizes that you need. Great feature!

I was looking for an image on google image search this morning and found that they had added huge image searchThanks google!

If you are looking for a dual monitor wallpaper (2560×1024) in one of the following categories then dualmonitorbackgrounds.com is the site to see. Abstract Animal Astronomy Celebrities Computers Crafted Nature Gaming Industrial Macabre Microscopic Mobile Technology Music Nature Popular Culture Science Fiction Sports Vehicles

wallpapers (1024×768 minimum) is the mother load of high res flickr groups. It is chock full of images tagged with wallpaper at a minimum resolution of 1024×768. 36,669 images and counting. This will take a while to go through.

Professional Wallpapers hosts a few HD images in a number of different formats. including 2560×1600, dual monitor, HDTV and PSP/iPod formats. Nice work.

desktopography is an exibition, a showcase of nature themed desktop wallpapers created by designers worldwide. This site is awesome! great visuals and great music! Lots of great, hi def and large format wall paper and all around great design. Check them out.

dual-display.com hosts alot of great dual monitor wallpapers and other useful stuff.Check out their tutorial on making your own dual display wallpaper.

Plasma Design has several large 4:3, 16:9, dual monitor wallpaper and 30" Display wallpaper designs. They have 3 flavors Aqua, Landscapes and Abstracts. Membership (£7 fee for lifetime membership) is required to access their collection which consists of over 200 images.