Reputation systems, like ebay's seller ratings or amazon's Top 1000 Reviewers, are simple but effective ways to get people to contribute to an online community in a certain way. I'd like to have some reputation rankings for frassle. How should I construct these? How would I measure useful contribution to the frassle community?

A related system would be ratings for websites linked from frassle. This is a simple addition to frassle's note system but offers an easy way to drop useful data into frassle. I should sketch out a data model for this tonight.