BOULDER, Colo. — Planning a trip can be as much of a pain as getting stuck on a delayed flight.

A new Web site called TripIt came to the rescue as I was planning three out-of-town weekends in a row this fall.

Despite a few minor flaws with the free service, TripIt is a wonderful, easy-to-use product that's bound to come in handy for the holiday trips ahead — whether you're visiting family in a major city or going hiking off the beaten path.

To get started, all you need to do is forward all the e-mail receipts from airlines, hotels and car-rental companies. Then you could easily add driving directions and other useful notes.

Because I was using an e-mail account TripIt didn't recognize, the service automatically generated a TripIt account and password for me the first time. That's a wonderful touch, though I later wished it didn't create a second account for me because I was using a second e-mail address. I had to manually merge the two, which wasn't too difficult.

For the Boulder trip, my United Airlines flight confirmation was automatically converted into a TripIt itinerary marked Denver, for the destination airport.

TripIt pulled the relevant details such as flight times, seat number and the availability of meal service. It checked industry databases for information not on the e-mail — in this case, adding the aircraft type.

A map of Denver was also automatically added, along with average weather for that day from the past 25 years. (TripIt doesn't give forecasts because often the trip is weeks or months away.)

There were a couple of forwarded e-mails the service didn't recognize, including a confirmation from the marathon I went to Boulder to run. But the service simply set aside the item, which I could easily move to the proper itinerary.

I could add personal notes, such as how to find the shuttle to Boulder and where my friend was going to hide the apartment key. I also added details about things to do, including a visit to the house from the Robin Williams TV classic "Mork & Mindy."

Finally, I added some driving directions — to my friend's place, to the marathon start and to Mork and Mindy's house. TripIt nicely integrated the map tools powered by Google Inc.

Along the way, items get sorted by date and time. Friends and travel partners can follow along — you can give them full editing privileges or just the ability to view your trip.

I finished by printing the consolidated list to take on my trip, and I found myself consulting it several times at the airports and during my stay in Boulder. Perhaps if I had an iPhone to access the Internet on the go, I could do away with printouts completely.

I encountered a couple of glitches, many of which have since been fixed since TripIt opened to the public in September — a sign its San Francisco-based operators are working to improve the service.

But the system still assumes "a.m." unless I specify "p.m." or use a 24-hour format, and I couldn't enter a time range — such as for a daylong event I could drop by anytime.

These quibbles are minor, and TripIt can't be blamed for the shuttle driver getting lost in Boulder, or for me missing a spectacular view because I was too busy sending text messages.

Back in New York, I had three days before my next trip, and in just an hour or two, I was able to get my entire itinerary organized. TripIt automatically recognized my car-rental reservation made through Orbitz and flight from Continental Airlines — the seat number was missing this time, however.

I manually added trains to the airport, along with addresses and directions for wedding events in the Napa Valley north of San Francisco. I forwarded my hotel confirmation, but because it wasn't one TripIt recognized, I had to manually move it to the itinerary.

Information on the flight's on-time performance would be nice. I also could have used a packing checklist and perhaps tips on complying with ever-changing security rules.

I was getting the hang of TripIt by the third trip, to Hartford, Conn., for another marathon, and thus had time to come up with suggestions for improvement: