Fnd - Browse Apple App Store and iTunes on the Web
AppRecs - AppRecs sorts through reviews in the App Store and automatically helps you filter out inauthentic results.
Knicket App Search - The future Wikipedia for Apps
Cydia - An alternative app store for jailbroken devices.
Zestia - Zestia is a mobile app designed to assist you in organizing your hectic schedule, social life, and professional persona.
AppSales - Find the best Android apps and games from Google Play that are currently discounted or free for a limited time