AppShopper - Mac Apps, Mac App Store, iPad, iPhone and iPod touch app store listings, news, and price drops
Zeplin - Collaboration app for UI designers & frontend developers
AppAgg - Application Aggregator
Mightytext - Send & Receive SMS Text Messages from your computer. Sync'd with your Android #
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.
ActiveWords - Auto correct on steroids