Windows XP and Vista only: Dual monitor utility DisplayFusion can set different wallpaper images for each of your desktops or stretch an image across desktops.

One free utility which sets per-monitor wallpaper OR stretches one panoramic image across two screens is the previously posted DisplayFusion, pictured to the right (click to enlarge).

Dual monitor setups are proven to increase productivity, but the trickiest part is that, well, you have to deal with two monitors. Avoid the annoyance of getting things to line up perfectly and ...