ideas for fun contests at fly-ins

I'm organizing a fly-in coming up in a few months and would like to have
some fun activities or contests. So far we're thinking about a spot
landing contest for arrivals and a precision flour bombing contest during
departures. Pilots can win prizes like a GPS or new headset or something.
Also planning on door prizes like shirts, case of oil, etc. Of course we'll
be serving food too.

Does anybody have ideas for contests or other things to draw in participants
? Anything you've seen at a previous fly-in you thought was cool ?