Last year I ran a session of Maid RPG for a few hours.
Ive been thinking about doing it again, but I need to see if my group is down for it or not. Otherwise I dont have a problem with randoms joining.
I might also run a session of Valor RPG
instead, because that game always deserves more exposure.
EDIT: Though I probably wont be able to schedule a time easily until I know the event schedule, and even then getting my group to do something at a certain time takes effort, so it would most likely be a spontaneous event sometime during slow hours.
Though if memory serves I do also remember they did have D&D events on schedule last year or a few years back, so that's always an option.