I have a twofold request here:

1. We should have the option to remove a background image from a project after we upload one. I uploaded an image that didn't work well but I had no way of reverting to the default background.

2. I would like the option to configure how background images appear. In my case, I wanted my background image to tile, but instead it stretched across the entire screen. (The most flexible way to handle that would be custom CSS for the project page, but I realize that could be...heavily abused.)

We could do 1 without much fuss, but 2 would be restricted precisely for the abuse factor. I see no problem adding this to our work queue; once it's done we'll mention it on the monthly news (and link that on this thread.)

One part of this request has been resolved with today's update- you can set your project's background display mode with the radio buttons under the upload form: