Diplomacy

Vanguard had a neat system of diplomacy in their game. They used a mini-game (card game in this instance) that allowed them to influence city and town priorities. These priorities shown themselves in the form of buffs to players who visited the towns who have been influenced by diplomacy. Such as using your diplomacy skills to focus the towns efforts towards production would generate a crafting buff for players who visited the town (1 hr duration).

Players where able to assist each other working towards the same buff, or compete against each other to prevent anyone from being able to get that buff. In the case of a crafter buff, the outcome wasn't overly important. But each town had multiple possible buffs to work towards, some of them quite useful such as a 5% hp buff. Since each towns buffs stacked with each other it was possible to get a strong assortment of buffs active. Strong enough to make or break a raid encounter vs. a specific mob. So the pvp aspect became an important aspect of a guilds ability to progress through certain content.

It would be great to see another system outside of combat and crafting for players to compete.