I chose the Apps Gone Free app and am quite pleased with it. Being able to look at all the apps that no longer cost money is great and since you can search back by days, you can make sure you haven't missed anything you can't do without.
I admit to usually just grabbing a free app card at Starbucks, but since I'm not that app crazy, I've never felt the need to scour the internet for free apps for my device. Now that I have this app, things might get better. Who knows, maybe I'll fill up my folders at last!