Also, here's the link that Jonbone sent around:

http://www.diplomacy-archive.com/resources/strategy/opening.htm

I often spend too much time going through these links when a game is starting. Really great stuff in there! Being a data geek, perhaps my favorite is this one:

http://diplom.org/Zine/S1998M/Anon/1901.html
which goes through the numbers of hundreds of games and just summarizes the numbers. Pretty cool.