A little while back, I wrote about an app called Corkbin -- it helped you track and share the various wines that you tasted while out and about. A few commenters asked for something similar for beer, and onTap is exactly that. It's made by the same company, and it serves the same purpose. When trying out a brand new beer (or an old favorite), you can snap a picture of it with your iPhone, log it, and even share it across Facebook or Twitter.
Just for fun, the app also has a dictionary of some beer terms, and you can also browse and view brews from around your area in order to see what people are drinking nearby. Just like Corkbin, it's a solid app, especially for those of us who enjoy a tasty beverage and trying some new variants from time to time.
Plus, you know, it's completely free. It's a great app to help you get the most out of exploring your favorite beers around town.