As you may know, Amazon has launched their own app store for Android. They promised a free paid app everyday.
http://www.amazon.com/mobile-apps/b/...ode=2350149011
Today's app is Collapse!
http://www.amazon.com/gp/product/B00...8&ref=mas_faad
Of course you need to have an Amazon account and the Amazon Appstore App to get these free apps.