Overgrowth Downloader is an Adobe AIR application that you use in conjunction with Overgrowth. The application shows you a list of all the avaliable mods and then allows you a one click install into the correct folder.

The application should run correctly on Windows XP, Windows Vista, Mac OS X and Linux (untested).

The project is open source so if you want to take a look at the code you can checkout the svn. If you make any changes the development team will be happy to accept patches.