From hackerspaces.org:

The OpenDoor Hackathon is a hackathon to benefit the members of hacker/maker/artist/co-working spaces by creating a standardized, Open Source access and membership management system that can be used by everyone. At the end of the hackathon, the systems (or subsystems) created by each space will be voted upon, and the best system (or combination of systems) will be chosen. Implementing the system afterward is, of course, optional.

For more information please visit:
hackerspaces.org