I'm not sure how complicated your itineraries are, or how much control you want over the process, but I've used www.tripit.com for about a year now.

You just forward your itineraries (air, auto, hotel) to the site, and it automatically puts them into an itinerary based on the dates on the email confirmations. It will store confirmation numbers, flight numbers, etc.

You can put in other plans such as meals, meetings, etc, along with their dates and locations, and then get turn-by-turn directions between all the events in the itinerary (optional, but very useful).

Anyway, the site is free to use.

mlk