1- App Crawlr
AppCrawlr uses a new method to combine advanced data mining and statistical modeling technologies to provide users with the most relevant and trusted recommendations for searching and discovering apps. Discovering new applications, understanding the general trends of what features users like and don’t like, comparing similar applications based on a multitude of factors are just some of the reasons why AppCrawlr is the most comprehensive search engine for discovering mobile applications.2- Apps Gone Free
This is a great iPad app that allows you to search for authored, handpicked recommendations. AppsGoneFree offers expert-picked top-ranked apps, for free
3- App Grooves
AppGrooves is a recommendation engine for iPhone and iPad apps. Discover the best among the more than 500,000 apps available from the App Store. To give you personalized recommendations, AppGrooves learns from your preferences: it will detect apps you have installed and then allow you to vote on pairs of your app