In the university, I really liked it that each directory had a sub-directory named .snapshot that I could use to restore previous versions of my files. The .snapshot directory had subdirectories named hourly.1, hourly.2, daily.1, daily.2, weekly.1, etc - they would contain the directory and the files as they were an hour ago, 2 hours ago, a day ago, 2 days ago, and a week ago.
Very nice, very cool.
I was wondering if there's anything like that available for Linux of Windows, since I'd like to have that sort of thing at home. How hard is it to set up?