Contributing to the efficiency of registration at the conference site, I think scanning conference badges would be a faster way to register participants in your programs.

Secondly, contest entrants can save a lot of time by just entering the number twenty (20) when they return wearing the T shirt at the conference.

We could however partially complete the registration process by scanning the badge. This would speed up the process a lot and would likely reduce the number of problems that users have with the process.

Also, we might as well do the raffle with code and avoid the whole ticket business altogether. Same as the car, just that it would run during the conference. In fact, we might as well award attendees points for posts during the conference towards the conference prizes as it would reinforce the idea of the site before they got onto the plane and forgot about it.