I meant to write about this months ago, when I first read about it on the TSMI blog: Eventful.com, a very sweet event calendar site that could be useful to meeting planners in so many ways (thanks to Rich for the reminder this morning via the MIMlist listserv).
Meeting planners can use it to find out what else is going on in town over their dates, to promote their events, and all that good stuff. But what's really cool is that attendees, exhibitors, and speakers also can use one of the site's tools to add their tagged events to their Web pages and blogs. And you can sign up to get alerts as new events are added. And you can add comments to an event listing (I haven't dug really deep yet, but I can imagine lots of "Come see us at Booth 324"-type of comments).
Anyway, go poke around and play with it. I'm thinking about adding a calendar to this Web page, except I don't get out too much anymore.