If you need something done, open sourcing an idea is possibly the quickest way. Because of the free-sharing spirit of open source, people give freely to an idea. Sharing ideas with people and allowing them to work on it gets them excited too.
Now.. what would you do if you have an army of people (with different strengths and skills as you) working on your idea, giving it a life of its own.
The idea is now something bigger than you.
Brief description: Sharing ideas with people and allowing them to work on it