TripIt
Enter TripIt.
This website and app organizes
The idea is simple: After you've signed up, simply forward confirmation emails to "plans@tripit.com" and TripIt will automatically create an itinerary for you. Or even better, you can set up the automatic forwarding process and you don't have to do anything to set up your itinerary.
Log in through either the app or the website, and you'll see all of your trip plans set up in one place. It also syncs everything with your calendar, making it super easy to view and share your travel plans with everyone else. You can send your itinerary to friends, family, or co-workers who want to know your travel plans.
TripIt
And all of this is completely free.
The company offers an upgraded service called TripIt Pro, which costs $49 per year. In addition to everything you get with TripIt, TripIt Pro offers things like mobile alerts telling you when your flight is delayed, canceled, or had a gate change; VIP privileges to other companies like Hertz; and notifications that tell you when you're eligible for flight refunds. It's like getting a full-time personal travel assistant who is constantly monitoring your travel plans.
Most avid travelers know about TripIt, but I've found that it still hasn't quite hit the mainstream yet. And that's a shame, because it's one of the best travel sites out there.