Good idea man!
I use these ones (I have more...but I didn't want to fill the page here ) all the time on my Nxx0 devices.
So rez's for these is 720x480 and 800x480.

[IMG] [/IMG]

The (obvious b+w) shots I took during various sabbaticals in africa and the arctic almost 30 years ago for some paintings I was doing ...I have them to remind me of the good times and cool people I've had the opportunity to hang with.
The stone hut I ran into during one of my cross-country ski jaunts.
The single figure is one of me....during a sketch and painting jaunt with friends during the fishing season up in the arctic....I found it pretty darn haunting.
The others are diverse film or tv icons ...the avengers...emma peel () ...
the prisoner..a dalek...from doctor who...
My "Punisher-ux" (coolest linux penguin around )
and some other cool walls (not my art....get bored with lookin at your own stuff....)...my kraken pulling a sailor under (my wallpaper for with a "mer"-ish theme for mer on one of my n800's)...ogham plates in wood...and painted prints....from a few centuries back...up until the beginning of the 19th....My stamp collection from when I was a kid ... and bookcases...I love my own bookcases and books...especially the feel of hardcovers...and found a couple good images of bookcases I liked that really "fit" the screen size well....so yeah...here is a few of my fav. cool wallpapers I keep gravitating back to...

As you can tell from a few of them I like having wallpapers that are unobtrusive and uncluttered for the central workspace...and so edited, cut and modified a few (especially of the iconic tv/film images) to occupy the far right rather than filling the screen and confusing the workspace...an aspect I like more than trying to find the cursor all the time with a beautiful but busy wallpaper.
As well you'll notice a few wallpapers where the image isn't the height or width of the screensize real-estate.
I personally don't care much for a busy background at the top of the screen under the status bar
or in the case of my N8x0 devices ...any wallpaper pattern that rides behind the left side bar. I don't like the serenity of the wallpaper being cut off abruptly.