Facebook expanded its Anti-Virus Marketplace today with the addition of eight new partners — Avast, AVG, Avira, Kaspersky, Panda, Total Defense, and Webroot. Today’s expansion allows users to download anti-virus software from these eight companies, in addition to security apps from existing partners like McAfee and Symantec. The new partners will also add to the database behind Facebook’s URL blacklist system, which pre-emptively scans trillions of links for malicious content. The AV Marketplace originally launched with five partner companies — Microsoft, McAfee, Sophos, Symantec, and Trend Micro — and, in the ensuing six months, has attracted more than 30 million users. By expanding its coalition, Facebook hopes to make its..