I've recently finished building a new generator app to help me build wordpress themes faster. Originally it was just to help my work go by faster, but I figured I might as well post it up for other people to use.
At the moment, all it does is create the info header of the style.css file, and take care of various theme settings like supports and custom post types or taxonomies. Not every possible option is there, of course, but I'm planning to continually develop this with new features as I go along.
So if you're a theme developer, try it out and let me know what you think. Feel free to suggest new features or point out any bugs I missed.