Playing Risk (ok-a-board-game-but-still) told me early on that everything happens on several levels (strategic, tactic, emotional ect) and you have to keep an eye on all of them (if you want to win).
(Yes, I've won several games of Diplomacy. The bitterness can last a while sometimes.)
For example, with my brothers and a few of their friends it is entirely expected that you will get stabbed in the back in a game if it helps the other guy win. There is a lot of guarding-our-flanks with that crowd. It's totally normal and expected, however some people have more of a reputation for it than others, which can lead to some players being unable to make any pacts without excessive bribery.
On the other hand, my current social peers are paragons of morality. If someone says something regarding the game, no matter how casually, they will be bound do that for a reasonable duration. Breaking this code creates a reputation which will carry over for the next few games and you'll find very few people willing to ally with you without stringent conditions.
Another odd example is playing multiplayer Magic: the Gathering. Throughout our time there have been a few decks that may not win often or quickly, but when they get going they become unstoppable, kill everyone in a single turn, or create a global effect that makes the game "unfun" for the other players such as destroying all their creatures and lands. Some of them have gotten such a reputation that certain players have only to play a certain spell on their first turn and the rest of the table will immediately focus on killing that one person first.
My fiancée will always put the dagger in my back in games. That's love, I guess.
take Junta http://www.boardgamegeek.com/boardgame/242
If you want to lose your friends more quickly, you should try Kuhhandel (http://www.boardgamegeek.com/boardgame/1117). That's poor evil `attacking', bluffing and second-guessing. (Unfortunately alliance are not common, so you do not get to break your word and stab your friends. But still a good game. :)
The communities are generally pretty small.
My experience in playdiplomacy.com is that it doesn't feel like a bunch of strangers after a couple of games, especially if you go to the forums - since playing diplomacy (with good players) normally involves quite a lot of talking, you can make somewhat more significant ties than in other online games.
Perhaps we should organize a Hacker game once? Even if we can't find seven diplomats (+ a GM), there are interesting variants for a smaller number of players. Like `Hundred' or `Sail Ho!'.
Ido, what do you think of this article: [http://www.diplom.org/Zine/F1997R/Windsor/lawdip.html]?
For a lot of the web based ones (including the site I mentioned) you do not need a GM, it is arbitrated by the computer.
It also works a lot quicker and is more user friendly than PBEM.
However the typical workload for a GM is far lower than without computer arbitration, of course. And you can read all the negotiations, if you want to.