Anyone who's read the official forums lately has probably seen a raft of complaints directed at players abusing the dungeon finder and vote to kick features. It's a reminder that people will always figure out a way to twist a system to their own benefit. The most upsetting technique I've read about is two hybrid DPS in cahoots with a third DPS queuing as a tank/healer duo, getting an instant invite to dungeons, and then pressuring the two other members of the party to shoulder the tank or healer job. If they don't or can't fill these roles -- kick 'em after the 15 min grace period and requeue themselves as straight DPS. Voilà -- they are now at the head of the dungeon queue for the next tank or healer! Is it any wonder that players find this enraging?
Heartbourne of Lore Hound offers an analysis of some potential solutions to dungeon finder abuse. As he observes, a proposed rating system for players could be easily abused on its own, so maybe that's not the best way to go. However, I find his suggestion of a social networking angle to be pretty interesting. What if there were a priority system to be grouped with players you met and "liked" before? What if guilds across servers could "friend" each other and form pools of players from which to draw 5-man groups?