I recently signed up for Upcoming, "a community for discovering and sharing events. It can help you find stuff to do, discover what your friends are doing, or let you keep private events online for your own reference."
LawyerKM mentioned the service in his Blog Buddies post. I am willing to try out new things (especially free things) and see if the are useful or potentially useful.
I created a profile (Doug Cornelius on Upcoming). I added some events and joined a group on knowledge management and one on enterprise 2.0. I also managed to add a few friends.
For example, the Enterprise 2.0 Conference was already added as event to Upcoming. I added the Knowledge Management 2.0 - Real or Hype? symposium being run by the Boston KM Forum.
The site is rich in RSS feeds. You can publish a list of upcoming events and you can subscribe to your friend's upcoming events. I added my Upcoming events to Dougs' Lifestream and Doug's FriendFeed. I also subscribed to my friend's events in my Google Reader. Upcoming is also leveraging the Yahoo Pipes tool to custom your RSS feeds.
Overall, Upcoming seems to be a great way to discover new and upcoming events. Upcoming is also a way to promote any of your upcoming events.
Of course, with any social media site the power of the site is based on the number of people and their activity.
The biggest problem I have with Upcoming is that it does not allow you to import a list of contacts to see who is already using it. I managed to find a few. But it is rather hit or miss. I threw in the names of few likely subjects and found a few. The site also defers to a user name rather than a real name so it hard to distinguish the person from a list of attendees to an event or those watching an event.
It looks like Yahoo recently acquired Upcoming so there may be some changes in store. I would recommend that you sign up for Upcoming and give it a try.