yeah..... i pretty much get all my 1680x1050 wallpapers from InterFaceLift (mostly due to the fact that 1680x1050 wallpapers can't be uploaded here in the wallpaper thread unless rar'd..... and now that themexp.com sucks. who wants to run an installer to install a wallpaper to somewhere on your hard drive and clutter your computer with a boatload of crappy uninstallers for said wallpaper too? sure as hell know i don't).
well.... DeviantArt does have an entire wallpaper section dedicated to widescreen/dual-screen setups. if i remember correctly.... in the categories menu, it'd be Customization - Wallpaper - HD/Widescreen or somethin like that. i found some awesome ones in there just browsing through. the one that i'm using right now from DA, and which i like quite a lot, is called "Behold the Eclipse"