Having a dotfiles repo can be a great way to have a central place to store configuration files that you may want to use across different computers. Also, when you get a new computer or change jobs, you can quickly get your system up to how your old one worked. I didn't use the idea until relatively recently, but I'm glad I started it.
Before I get into more details, I want to acknowledge that the following videos and dotfile repos helped me tremendously in getting started:
Thoughtbot Video on Dotfiles
Thoughtbot Dotfiles Repo
Chris Toomey Dotfiles Repo