Dopplr, which I wrote about a while ago, has been quietly getting better. It supports Open ID. I can subscribe to my trips using iCal (or in fact anything that understands the Webcal scheme). Best of all, it now knows a bunch more places – nearly 200,000 cities, actually.
Here are some of my trips for the rest of this year.
I’m a happy user. If you fancy trying it, and we’re likely to want to share knowledge about when the we’re traveling, do let me know so I can send you an invite.