The Secunia Personal Software Inspector (PSI) Beta is a free security scanner that identifies vulnerabilities in non-Microsoft (third-party) programs which can expose PCs to attacks.
Identifies missing security updates on your PC
Covers programs and plug-ins from thousands of vendors
Extended automatic update using the Secunia Package System (SPS) NEW!
Dramatically simplified user interface NEW!
If you like, Secunia PSI will silently update your non Microsoft programs automatically. This would be a great feature for those who never update, and just surf willy nilly. Not only for them, but they would benefit the most IMHO. I personally run PSI manually, and update anything I haven't already. I will be installing this version, and testing it myself. Source