Collection of free app to Iphone

http://www.148apps.com/top-apps/top-free-iphone-apps/

http://appshopper.com/bestsellers/free/?device=iphone

http://freeappaday.com/

http://www.tomsguide.com/us/pictures-story/282-free-iphone-apps-ios.html 

http://iphone.appstorm.net/roundups/100-incredibly-useful-free-iphone-apps/