Let's take the planar rune off of Kutty for instance. Last night I went to help a guy get his, and there were 3 people there already trying to get theirs. Now under the current system you have to stand around for an hour and kill him 4 times to get 4 runes. Why not just have Ankhulure give out a quest to go with his current dialogue, and when you kill Kutty it flags the quest as complete or something and then Ank gives you the rune?
This would also limit the amount of certain items (quest rewards) in the game as well if you made the quests non-repeatable, increasing the value of stuff and negating farming of certain monsters.
I realize it's probably too much work to redo all the current quests, but it's something to keep in mind for future reference. Especially with NWN2 around the corner.
This leads me to my next suggestion, some sort of group xp bonus. Currently you get more xp per kill if you run around by yourself and kill things. Granted if you have 2 people you can kill things faster, but then the xp is cut in half so I suppose it balances out.
Maybe that wouldn't work after all, it could be hard to balance. I'm just trying to think of ways to encourage grouping.
Feel free to chime in here.