TripIt is a personal travel assistant that automatically organizes all your travel plans. TripIt is free and makes it easy to...

* Quickly organize your vacation and business travel - no matter where you book
* Automatically get itineraries with all your plans, weather, maps, restaurants and more
* Easily access your itineraries via paper, email, personal calendar or mobile device
* Share your trips and see where you overlap with friends and colleagues

See About Us for more.

This is like Dopplr, but actually useful, because you populate our tripit by forwarding your ticket/hotel/car rental confirmation emails to plans@tripit.com. It auto populates your tripit account and sends out an iCal stream of your travel.

Nice when you work in an international company and you never know where anyone is, as they don't manually update the calendar.

TripIt | Organize your travel