I was looking for the exact same feature (add our own pictures)

Totally agree with above, definitely should be able to add own photos.

I think the ability to set our own theme would be enough. As far as I can tell, the theme has no effect on anything but the background picture. If this is true, there are plenty of other websites where users can find background photos that they would like.

Ability to upload a custom background would be sweet.

It would be great to add your own pictures to themes (background picture). Maybe the pictures must not be hostet on the RTM server, perhaps just link to a picture an the web.

This would be cool, but I can see some issues with it.

1. RTM would need to have the server space to host the pictures of everyone who wants to do that.

2. If holl0w's suggestion is implemented and RTM grabs a picture from a link, how would copyright law come into play? Also, if that linked picture was suddenly gone, or if the website that has the picture goes down, what would be shown? A broken picture icon?

It may not be worth the developers time and effort to implement this.