I'm envisioning a scenario where I could make my entire C:\ drive a checkout of a SVN repo. Then after I install a new program, I could go into "View Modifications" and see what changes it has made to my computer. "Oh, it created a log directory here, put some dlls here, and made an annoying temp folder in my User directory." Then, I would commit the changes I liked to the repo with a comment and anytime I wondered why some oddly named folder is somewhere, I could just check the SVN log.
This would be useful for a number of reasons. It would be a good learning tool for what installer programs are doing to computers. It would provide a semblance of a backup system, though it wouldn't be a fully functional as some other backup solutions. It would provide an incentive to clean up temp files more often. But most importantly, it would give you the power over all the crap that is installed on a computer over time by providing metadata and easy ways to revert changes that you don't want.
Obviously, this doesn't have to be SVN or even a version control system. That is just the first thing that pops into my head when I think of the problem I'm trying to solve. I'm not having any luck finding other people who have solved this problem, but it seems like it would be incredibly valuable. Does anyone know of a way to accomplish what I'm trying to do?
For realtime tracking when file or directory changes you can use inotify on Linux or FileSystemWatcher on Windows. Combine with rsync to get delta.