A smooth trip requires organization. TripIt can automatically scan your email inbox for confirmations, reservations and frequent flier points, and then bring all your trip details into one itinerary. It will even sync up with your calendar, and notify friends and family.
If you're not too keen on letting TripIt rummage through your mail account, you can just forward all relevant trip messages to a TripIt email address for the same results. TripIt is free for Android and iOS.
Android | iOS