My husband and I just took a much needed vacation to Southern France. For the past several years, we've been using TripIt to organize, share, and coordinate all of our travel plans. Instead of using multiple apps or heaven forbid an old school paper file, we simply email all of our confirmations to firstname.lastname@example.org from a known email address. TripIt then imports all of the relevant details (location / time / flight numbers / restaurant reservations) into your account so that you have everything in one place. On this trip we took planes, trains, and automobiles and we moved around quite a bit. So, we had many details to manage and TripIt is a wonderful tool to keep things on track.
There's a free version that provides quite a nice suite of features. However, I prefer the paid version ($49 annually) which gives me the ability to grant family members access to all of my trips automatically, track points and miles, get real-time flight alerts, and be notified if a previously purchased airfare has dropped so that I can request a refund. There are many more benefits besides these, but these are the ones that I enjoy the most.
Here's a link to a feature comparison on the TripIt website.
TripIt is one of my most used apps as I travel a fair amount. It's also nice to have an archive of past trips so that you can find that hotel that you liked, or reminisce about that restaurant that you went to or concert that you enjoyed. It's all right there at your fingertips by web / smart phone / tablet.