I tend to use the same ones for a long time since it's hard to find decent wallpaper for dual-monitor setups. Using ordinary wallpaper results in Doublemint twins. I try to find things that break naturally in the center so that each half looks okay on its own screen, yet, if you squint out the break, looks okay in full..
Currently on my XP box now, is a photo I took. This is the new "signature" bridge here in downtown Rochester, which carries I-490 across the Genesee River. In the foreground is a dam that keeps the river navigable south to the Erie Canal.
In the past, I've used this satellite composite from NASA, which I cropped and adjusted
Under Linux, I use a similar NASA composite
Huh. I seem to prefer dark blue too. Never really paid attention to that before.