semi off-topic: Prof. Pierce's research group created the Unison bi-directional file synchronizer and open-sourced it. It's a really useful tool that I use literally every single day to keep my files synchronized. Think of it as a predecessor to dropbox, without the UI polish ;)
Additional interesting fact, unison is written in ocaml. Very cool to see interesting systemsy software written in a functional programming language. I'm very excited to peruse it later.
Unison also hasn't been updated at all since the original authors stopped working on it, as far as I can tell. It's only one data point, but it does suggest a downside of using ocaml for open source software...
http://www.cis.upenn.edu/~bcpierce/unison/