Secunia PSI (Personal Software Inspector) is a free security tool designed to detect vulnerable and out-dated programs and plug-ins that expose your PC to attacks. Attacks exploiting vulnerable programs and plug-ins are rarely blocked by traditional anti-virus programs. Secunia PSI checks only the machine it is running on, while its commercial sibling Secunia CSI (Corporate Software Inspector) scans multiple machines on a network.
For downloads and more information,
visit the Secunia PSI homepage.
This tool is the best way I've found of keeping my applications up-to-date. It even finds weird left-behind DLLs from broken installations and things I'd forgotten I had installed. The automatic updates sometimes fail, but it never fails to tell me there's a new version available.
Secunia did a good job of locking down the interface. The service runs as administrator, and requires the administrator's password (via runas) to interact with the console. No privilege escalation here, thanks!