Hi,

Does it exist a module to change/load JPG wallpapers?

I know WallPaper changer 1.0 but it has no options (stretch, tile, ...) and doesn't support JPG files.

I remember seeing one while looking at a list of all the modules available..don't remember what it was called. Let me see if I can find it again

http://modules.shellfront.org./wimacpaper-0.0.3.zip
It's very simple. Just uses a !bang to change the wallpaper to something. I'm sure you could fiddle with it to make it work however you want