How about a simple system that lets you run a new kind of auction for an event with limited seating? Say you want 200 people to come to a networking event, the sort of thing that’s no fun if only a dozen or two show up… Instead of charging $50 a ticket, why not charge $1 for the first five tickets, $2 for the next five, and on to $500 for the last ten? You’ll earn just as much (if not more) but reward the brave who sign up early. (The folks who like to wait until the last minute ‘to be sure’ end up paying for the privilege). It’s easy to imagine a simple interface to set up whatever graduated pricing model you’d like.