I found something that might be an undocumented feature in the OnlyMe software....
If you load several background pics (you hotsync them as described), it will actually somehow store them all and cycle through them. So with (almost) every turn-off/turn-on cycle you get a different background pic to come up.... Thats pretty cool.
I only wish I knew hoe to uninstall them again, I mean specific ones. Anybody seen this yet?