Pretty much all combat leveling here is done by the pull-kill-pull kill method.
The only time we fight multiple mobs simultaneously is when we get adds, particularly on treks and bad pops and such. It is avoided as much as possible, with the exception of chaining. But that's still only two mobs.
To mix up the level grind, perhaps it would be interesting to have some species of herbivores that were beyond "social." This meaning absolutely unseperable from the group of 5-10 they wandered with, so to take one on there would be no choice but to take them all on simultaneously. They would have a significant XP bonus for this increased difficulty and only mid to large teams would be capable of taking down a group because it would require multiple tanks and healers.
If you're going solo or in a small team, just avoid them. And of course only herbis. I think it would be fun for something different and to encourage more people to level in large teams, maybe even help the highest level people who are having difficulty finding anything to hunt with more than 2 people.
If balance is an issue, introduce it first with only a mild XP bonus. The playerbase will determine if the groups are worth the trouble or not. If no one hunts them, nudge up the XP a little next patch. Continue that until they start to see some action but before everyone and their mother is hunting them all the time.
Yes, I know there are more pressing issues. But I think we all enjoy talking about possible game enhancements even if we don't expect them to happen.

Thoughts, comments, suggestions, and flames welcome
