$HOME in Subversion
Keeping my $HOME in Subversion has made my life much easier. The chief benefit is the ease at which I can create and synchronize dotfiles across different machines. In the past I have had to figure out which box has a particular version of a config file and then manually copy it over. This is just a waste of time.
This method also benefits from all the goodness of version control: backups are easy, history, etc. I can manage all of my config files just as I do my source code.
I found a great tutorial that I used as a starting point. I highly recommend you give it a try. Once I start to deviate from the tutorial a bit more I write my own how-to.