Apps Gone Free
This is one of my personal favorite apps. I frequent it on a daily basis. This app gives a list of several paid apps that are free for the day. The apps don't always stay free for the whole day so if you are interested in it, download it while you can.
You can search by date. This is particularly handy if you weren't able to check one day. You can go back and search over the past year. It also shows the original price of the app. If it contains a red slash through it, that means it is still free.
When a free app opportunity has expired, it will be updated and labeled within the app.
You can read the descriptions of each featured app. If it peaks your interested, select your correct device. Then you can click on the free button and it will direct you to the app store so you can download the app.
This app is a wonderful resource if you are interested in free apps of the day. You can set it to notify you when the free apps of the day are released for you to purchase. I've personally found many interesting apps from this app. I highly recommend it!