AppShopper - Mac Apps, Mac App Store, iPad, iPhone and iPod touch app store listings, news, and price drops
UCheck - UCheck is a tool that will help you to keep your software updated.
AppAgg - Application Aggregator
Avira Software Updater - Application that searches updates for software on your computer
AlternativeTo - AlternativeTo lets you find apps and software for Windows, Mac, Linux, iPhone, iPad, Android, Android Tablets, Web Apps, Online, Windows Tablets and more by recommending alternatives to apps you already know.
HEIMDAL FREE - HEIMDAL FREE is an application to automate your device software updates in order to improve your security.