CiviCRM User Summit Sept 2016 - Any last minute ideas on how to convince another 20 people to register
I received a somewhat clever promotion from DonorDrive yesterday to encourage behavior.

They were looking for survey respondents- anyone who filled out the survey within 25 minutes got an instant Starbucks gift certificate for $5 (printable).

I don't even like Starbucks, and I fell for it. 

Maybe you could use this technique somehow?