May I humbly suggest my book, Building Web Reputation Systems from O'Reilly? Our blog on Reputation is here: http://buildingreputation.com and a freely accessible draft of the book is here: http://buildingreputation.com/doku.php

Here's a community based approach detailed in my book Building Web Reputation Systems from O'Reilly http://oreilly.com/catalog/9780596159801 From Chapter 10 - Case Study: Yahoo! Answers Community Content Moderation: [Wiki version here -> http://buildingreputation.com/doku.php?id=chapter_10 ] "In summer 2007, Yahoo! tried to address some moderation challenges with one of its flagship community products: Yahoo! Answers (answers.yahoo.com). The service had fallen victim to its own success and drawn the attention of trolls and spammers in a big way. The Yahoo! Answers team was struggling to keep up with harmful, abusive content that flooded the service, most of which originated with a small number of bad actors on the site. Ultimately, the answer to these woes was provided by a clever (but simple) system that was rich in reputation: it was designed to identify bad actors, indemnify honest contributors, and take the overwhelming load off of the customer care team. Here's how that system came about."