While your Mac should automatically alert you to updates downloaded from the Mac App Store, you may not be aware of updates available for software purchased elsewhere. MacUpdate Desktop 6 alerts you to updates on thousands of software titles, as well as enabling one-click installation of new apps.
The software and corresponding MacUpdate account are free – for up to five updates a month. Unlimited updates will cost you $20 a year.
The video below gives an overview of how it works, and you can download the software here.