Do You Post Events?

Some of the social networking sites have events posting. It's kind of like a calendar where you can post events you are doing or join in events that other people are doing. The cool thing is You can make them public or private so you can use this feature as a private calendar if you want to.
You can also use the event feature to invite other people to join your event. I suppose this could be used for just about anything. If you use the event feature on your social networking site, what do you use it for? If you don't use it, what would you use it for?
~admin