I volunteer with an organization that puts on science fiction conventions. I was the co-head of the Programming department at a Doctor Who con this past weekend (you may have noticed the link in my signature). I estimate that I've worked on something like 22 conventions over the past 25 years - which included chairing one and co-chairing another within three weeks of each other, and working on a media con and a Worldcon simultaneously - twice.
It gets crazy from time to time, especially in those periods when I'm getting 200 emails per day, but I enjoy seeing hundreds of people derive joy from something that I've helped put together.
Here's a little tidbit from this past weekend - I wasn't directly responsible for this, but someone who reported to me put together a number of games for the kids which involved our local contingent of Daleks: