Where do you find specialized developers?

I'm researching this to help out a medium-sized company that works on very specialized and new technology (e.g., Google Glass). There a sort of go-to place if you need something out of the ordinary.

Ideas so far:

- Specialist job sites... but where are they? - Host events for developers (covering the specific technology) - Employee referrals - Telecommute/remote workers - Train developers in (or support learning of) new technology

What else should they be doing?

Does anybody have experience with this?