I've been travelling quite a bit over the last couple of months -- I’m on a plane or train or both at least once a week. One of the most painful parts of travelling is keeping track of my itineraries: carrier, airport location, departure times, arrival times, confirmation numbers, hotel names and locations, etc. When you're moving around a lot, keeping track of all of this can be a complete pain.
TripIt is an iPhone app that solves this problem. Anytime I book a train, plane, hotel or dinner reservation all of the relevant information is imported neatly into the TripIt app. When I open the TripIt app it shows me all of my trips in chronological order. When I click on an individual trip it shows me all of the relevant information for each flight, train, hotel and dinner reservation. TripIt takes a good chunk of stress out of traveling and I never have to carry print outs or search through my email to find a confirmation number.
There are two ways to get your itineraries into the TripIt app. You can either forward your itineraries to the TripIt email address or you can set it up so that TripIt automatically scans through your email every 10 minutes looking for itineraries. I've gone with the latter option and it's worked great.
TripIt makes money by offering premium packages -- TripIt Pro and TripIt for businesses. You can see the different product features here. So far I've opted to stick with the free version.
If you're looking to reduce some of the stress that comes with travelling frequently, TripIt is a no-brainer.