Chaos my favorite kill'em all multiplayer game style.
Team Multiplayer Rules lists possible rules to use in various sized team games.
2- Headed Giant is a 2 on 2 multiplayer game with it's own special set of rules.
Multi-player Styles of Playing Different people play different ways. These are some of the more common styles.
If you have any questions concerning multiplayer games, please ask me at archive@mich.com I will try to answer them as quickly as possible.