[Kipper is King]

The potential for abuse with the system you are mentioning is higher though.

If poster X doesn't like poster Y, they could just give a negative vote to every single one of their posts, for example.

REDVAN's example of a system where you need a certain number of +'s or -'s before you skill points fluctuate might work well. That way, if two posters don't like each other, and are heavily biased, the impact would be minimal.