I love finding useful free apps. Today I'll steer you to GateGuru, a free app that will help you navigate airport terminals and find food, ATMs, conference rooms and shops. The app was featured in an iPhone TV ad earlier this year, and it has been updated since then with some new features and bug fixes.
GateGuru starts by locating the nearest airports via GPS (U.S. and Canada only, unfortunately). You can also type in an airport's three-letter identifier code or city name. Once your airport is identified, you can select the main terminal or a particular concourse. You'll get a map and a list of what's there, be it food, shops, or services like shoe shine stands or free Wi-Fi.
You also get user-supplied ratings of shops and restaurants. Sometimes there are photos as well. This is all pretty handy, especially if you are in an unfamiliar airport. You can also add your own photos and reviews.