Here's a potentially very useful service for traveling geeks: TripIt. If you forward your electronic travel confirmations (from the airline, the car company, the hotel, etc) to it, it will intelligently collate them all into one place, parse the information, and add related information as well, such as maps, weather, events (from Eventful) and photos of where you're going (from Flickr). The goal being to replace all your pages of printed confirmations with a single online page that has all the relevant info, nicely organized for you.
The TripIt "Itinerator" has a social function: If you set up travel friends who are going on the same trip, it will collect all the data in one place, and will, from that point on, let you share your travel calendars if you like.
Now hinted at here at TechCrunch 40 -- but very important, I think -- would be mobile access to your personal trip pages. While the really reliable mobile output for TripIt is the printout from your smart itinerary, having a mobile-friendly Web page with useful links (local taxi companies, current weather, stuff like that) automatically created for you could be even more valuable.
It's unclear to me if TripIt is sustainable as a standalone, consumer-facing company. The service looks very useful, but I'd hope to see it embedded in booking sites like Travelocity and Orbitz.