I've always hired only ridiculously brilliant engineers and those that were either entrepreneurs or entrepreneurially minded (i.e. attended startup weekend, contributed to open source, blogged, etc).

The best way to find them is to go to the events they attend. Typically it's developer meetups, open source or programming language oriented conferences, etc.

To add a heightened filter, maybe only entrepreneurial oriented events like Business as Software, StartupSchool, or StartupDrinks.

Also, using Angel.co to find companies that were once listed, but didn't raise or seem to have "Sunsetted" might be a good strategy.

The question I always ask myself when I'm about to do sourcing for talent, or marketing is:
1) Who do I want, or what are examples of those people in the real world?
2) What places do they go/hangout, tools do they use, news sources they read, etc?

Be strict with your filters and you should find some candidates... the hard part is convincing them that your project is more interesting then their current job/project/ideas/company/etc - cause these people typically have many options for work.