I've found Secunia to be a very valuable resource for checking the security status of all kinds of software. So I was very interested with the news (via the Testbed blog) that they now have a Personal Software Inspector for checking whether any software needs updates.

It is still in Beta the moment but still sounds very exciting to check the status of software without going through a different website for each one.

It sits in the Notification Area and monitors in the background. The only problem there is increased demands on the computer, but I consider that a worthwhile tradeoff for staying secure.