I've patched mtftar to build on Mac OS X. The code can be found on GitHub: https://github.com/sjmurdoch/mtftar
Where to put the Backgrounds
Firstly, thanks to all those who worked to move Themes.org over to Freshmeat, it's much better now.
However I can't see where to put background images that are not associated with any particular Window Manager. I have a couple that I would be happy to upload again, but there doesn't seem to be a section for these at the moment. Are there plans to create a new section, since I think this would be a good idea?