[Communitivity]

That is an excellent observation. I was in the Open Reputation Management Systems Technical Committe at OASIS. During the initial discussions there we mostly agreed that reputation has to be multidimensional, for exactly that reason. I may have a great reputation in XML, but have credibility in .Net. Popularity is still a concern, but there mechanisms that can mitigate this. For example, a feedback mechanism where the reputation changes of someone feedback into the reputation of people previously voted on that persons reputation. So someone who used a mechanic with a high reputation and down voted him when they found out his reputation was unwarranted would also impact negatively the reputation of the people who gave the mechanic the unwarranted increase in reputation.