TripIt is a site that allows you to track your travel planning. The cool part of the site is that it is easy to add your travel plans to your profile. When you receive an email confirmation from the airline, hotel, or reservation site, you just forward it to email@example.com. It sees that you have sent the mail and adds it to your itinerary. When I was traveling a lot for work, this would have been tremendously helpful. I frequently made plans through a number of different vendors and this site would have allowed me to easily consolidate all of the information. As an added bonus, you can choose to easily share your calendar with friends, coworkers, and family members.
[Found from a link on Joel On Software.]