Slashdot links to an interview with Gabe Newell, of the Valve fame. I think this idea is pretty interesting:
The issue that we’re struggling with quite a bit is something I’ve kind of talked about before, which is: how do you properly value people’s contributions to a community? … An example is – and this is something as an industry we should be doing better – is charging customers based on how much fun they are to play with. … “So, in practice, a really likable person in our community should get DOTA 2 for free, because of past behavior in Team Fortress 2. Now, a real jerk that annoys everyone, they can still play, but a game is full price and they have to pay an extra hundred dollars if they want voice.’
Karma-based systems aren’t the easiest ones to figure out. But they have plenty of potential. Given enough will, effort, and tweaking, I think this can be done. How well it will actually work – remains to be seen.