Organizing a D7 hackfest

Hi all:

I'm working on a Drupal project (rebuilding the mathematics website PlanetMath.org) and we have a reasonable prototype, but I would like to get more D7 programmers involved as we move to "production".  My guess is that organizing a hackfest might be a good bring others in.  Right now I'm very much in the brainstorming phase, so I'm wondering:

 What sorts of things could we offer that would entice YOU to attend?

Cheers,

Joe

(holtzermann17@gmail.com)