I keep any sort of file I really care about in a personal svn repository. Mostly this is either code, PDF's, Word Docs, Excel, text files, and so on - Not too much video or anything like that.

I then use DatedBackup (http://datedbackup.rubyforge.org/), to backup the repos, and a few servers, which is basically a wrapper around rsync. It more or less mimicks the functionality of a simplified time machine without the gui - keeping snapshots at certain intervals, and deleting them when the drive gets full. It uses a technique similar to rsnapshot, so extra space doesn't get wasted by every snapshot.