This just in from Michael Feathers of "Working Effectively with Legacy Code" fame: a blog post on regenerative build tools. In the post, Michael describes an eye-opening practice related to continuous integration. Some smart people had the idea of running a script as part of a continuous build system that would comment out #include lines, one at a time, and then run the build. If the build succeeded, it meant that the include line in question was superfluous and thus could be deleted. Very interesting idea.
I bet this idea could be easily applied to Python projects, where you would comment out import statements and see if your unit test suite still passes. Of course, you can combine it with snakefood, a very interesting dependency graphing tool just released by Martin Blais. And you can also combine it with fault injection tools (aka fuzzers) such as Pester -- which belongs to the Jester family of tools also mentioned by Michael Feathers in his blog post.