AppMiner does not only provide free apps for you to download, but also help you track price changes of your favorite iPhone apps. So if one iPhone application is important to you, you could get it for a more reasonable price to help the developer to continuously improve the application.
AppShopper is a website for you to find free iPhone apps in Mac. It lists all the iPhone apps price changes in the app store, including those that have changed from paid to free iPhone apps. You will need iTunes and an account to download free iPhone apps to your Mac and sync to iPhone 4S.