MOST USEFUL FEATURE: TripIt indexes information directly from confirmation e-mails. Simply forward them to email@example.com. All the flight, hotel and rental-car information included in those e-mails is automatically entered into your traveler profile in chronological order, creating the easiest schedule you've ever put together. The feature works with confirmations from many top travel sites, hotel and airline sites, and aggregator or travel-search sites.
Another tool, TripClipper, lets you snag notes on destinations while doing online research. For voracious researchers, this takes the place of cutting and pasting all of that online research into a Word document.
NEEDS IMPROVEMENT: Manually inputting trip information can be a bit clumsy. One big complaint: all the separate boxes for street address, city and state. If TripIt can discern these various elements automatically from an e-mail confirmation, why do users have to enter them separately? Additionally, TripIt needs to more quickly make its services available on Facebook and other social sharing tools.
THE BUSINESS MODEL: Not surprisingly, it's advertising -- both contextual links and sponsorships. And TripIt hopes to introduce premium features in the future.