What makes a good code review meetup?

Has anyone pulled off what they think was a successful code review meetup?

We (the Portland WordPress Meetup) hosted a code review night last fall for our developer meetup with mixed success. Prior to the evening, everyone wanted us to do a code review meetup. It was like pulling teeth trying to get people to submit their code though, and we only reviewed a few the day of. Furthermore, we tried to do reviews live, which was time-consuming, had slow spots, and probably wasn’t the best idea.