is there any way you could add to pair images off, wile using the random desktop wallpaper function.
i like to have a random wall paper, but i also want my other monitors to match (but not have the exact same one)

maybe you could have the user add a suffix to the end of the filename, that is used for formatting?

IE it would pair images whos last 5 characters before the file extension matched..

well actually both would/could work the same way..
if theres only 2 images in the group, it would select 1 for each of your 2 monitors.
if theres 50, it would pick 2 (or however many monitors you have) at random.

heres a sample filename: rainforest.nature.jpg - where files with the nature suffix would be grouped

and a few afterthoughts/expansions to the idea;

maybe you could automatically change the users theme, based on this suffix (if any themes filename has the same suffix added to it)

also i would really appreciate a way to eliminate pictures that may not be suited for wallpapers from the folder. here are some criteria that would be nice;

-Resolution; (i would recommend you setting this resolution to scale with the users desktop resolution, and allow images no smaller than half the displays resolution, for height and width)
-Aspect Ratio; images who's aspect ratio is way off that of the monitor, should also be removed; IE an image taller than it is wide shouldn't be a wallpaper on a monitor with 16:9 aspect ratio, as it would look way to stretched..., NOTE: this same image would look great on this same monitor sideways, so you would need to detect monitor orientation to....
maybe for particularly wide images(something that's close to 32:9 would stretch 2 monitors nicely), try to stretch them across 2 (or more monitors) instead of adding a random one to each