My presentation at the useR! 2009 was an exception. I had the biggest audience ever. I guess that there were at least over 60 people in the room. Had I known this, I should have prepared a better talk to introduce our mi package. I did not control time well. So I have no time to go through real examples. Nonetheless, here is the link to the paper in case you were among one of the 60 people who might want to know more details about our mi package.
1. Big names. I am no big name. But the conference program did list Andy and Jennifer's name on it because they are coauthors. So I think people came for their fame. In fact, many people did ask if Andy and Jennifer were in the conference. Yes, this must be the major reason.
2. People want to know more about mi. The existing mi packages are really disappointing. So they would like to know the alternative. If this was the case, please do read our paper. I explain things better there.
3. My panel was the first panel in the first day. We have 450 attenders. And each time slot has 6 panels. So the number was about right. Each panel on the same time must be flooded with the same number of people.