Bukkit

What is the enhancement in mind? How should it look and feel?
Give virtual XP to players proportional to the damage they make to a mob.

If a player makes 50% damage to ender dragon, he will receive 50% XP, even if he isn't the one who will kill it. But only if the player is online.

Or if this is hard to make, an assist system will be easy I guess.

The players who assist receive Y XP.
The player who kill the dragon receive ALL XP - Y XP * assists but not less than Z XP

I have wanted to enhance the virtual xp system. I haven't time to change it much at the moment though.

I do like this though.

I would much rather have the change be directed toward the first person to hit it gets the XP.

If there is shared XP I would prefer it be tied to a group type plugin.  The above suggestion still doesn't resolve the core issue of someone taking xp from someone else.

For example:
Player A starts killing the mob.
Player B takes a pop shot at the mob

Currently:
Likely Player A, but could be Player B if he lands the final blow

Suggested:
Player B gets a portion of the XP even though he didn't have threat and only did 1 hit.

Correct Solution:
Player or Group who first hits the mob is the only player or group who can get the XP.  Tied to a timer so that if no hits are scored the timer expires and the mob resets it's status for a new player/group.  If Player A hits first and then Player B pop shots it then Player B gets nothing even if it is the final kill thus discouraging steals.

Additional updates to include a fix for:
Player A goes around hitting all the creatures he can see.  Player B then hits a target and it says "this player has already been attacked recently"  the damage can be blocked to prevent the mob from chasing them.  Thus Player A can not mob grief and trick player B into killing his gains.

@ryanwagner: Go

I see where you're coming from, but I think your suggestion is a separate one entirely. This one is: % of the damage done = % of the XP. It doesn't stop players from attacking a mob, but it does ensure that those who did the most damage get the most XP. That's what it's intended to stop: Player A doing 99% of the damage, then Player B coming in and popping the last shot to get all the XP.

Still a valid suggestion, but I think an enhancement where players or groups tag mobs and others cannot get XP or even damage it is another one entirely (although they'd work well together).

Experimental branch: https://bitbucket.org/fmp/controlorble/src/79b8de3ec7c0?at=expTracking