I know San Francisco International Airport fairly well since it is home base. I know where to find a cup of tea or a bottle of water just before I board my plane and the Duty-Free shop. But, put me in any unfamiliar airport in the U.S. and I will be on the lookout for the nearest directory.
Enter GateGuru. This is an iPhone and Android app that provides information for a specific airport’s restaurants, pubs, shops, ATMs, etc. It also includes the terminal and nearest gate location as well as rating. This convenience could come in handy when you have a short layover and are in need of reading material or some breakfast before your next flight.
Although this is only for U.S. airports, I would like to see international airports added as well.
pathwrangler.wordpress.com 
That is a great tool. I travel a lot and getting lost in a airport while trying to not be late for you next flight can be a problem sometimes