In a foreign airport? LoungeBuddy might come in handy
We recently came across an iPhone app called LoungeBuddy - we haven't used it yet but it's making the rounds on a number of travel sites and it seems promising if you're traveling to a new or foreign airport.
The way it works is you tell it what frequent flyer memberships you have, what airline you're traveling on, what airport you're in, and it'll tell you what lounges you have access to. The list is actually pretty comprehensive - ranging from various AmEx cards to whether you have a military ID. It'll also let you specify amenities that you're looking for (e.g. showers), which sounds pretty handy.
Drop us a line in the comments if you've used it and let us know what you think!