12th
TripIt is a site for organizing and sharing travel itineraries, It’s pretty simple in concept: just forward the confirmation emails you get during trip planning to TripIt, and they consolidate them and prepare a unified agenda. They further annotate this agenda with local area maps, links to contact airlines for confirmation, and other useful travel information.
The other big feature of Tripit is that it allows you to share itineraries with people you designate - very useful if you’re trying to coordinate a trip with business colleagues or friends.
TripIt is still in its early days and is still a bit quirky: They are still expanding the list of hotels and airlines they’ll accept confirmation mail from, and the browser support still has bugs. However, I’m already finding it pretty useful for travel planning, and I suspect this will increase as I add people to my network.