I run a start up called stakemyrep.com, an accountability platform where users can bet reputation points on each other to stay motivated. They create goals for themselves, earn badges and track progress on the leader board.
We're giving away flights to Japan as a prize to help promote the site, users can accept challenges for the parent competition or sub-competition we are getting rolled out with partner brands.
Here is an example of how that works:
The parent comp
[Imgur](http://i.imgur.com/mXOoXtK.jpg)
And an example child comp
[Imgur](http://i.imgur.com/byOwy3b.jpg)
Just thought I'd share it here. I've been doing this for a while now, have some pivot ideas that we're testing right now.
Regards, Thomas