I am now using developer IRC channels to recruit.
After exhausting agencies, linkedin, and adverts I was particularly frustrated by what I had seen and the quality of who we had interviewed.
So I asked the simple question, "Where do devs hangout?". And I'm not talking bars, I'm talking those who are busy actually doing stuff, especially if it's stuff they're working on in their own time (a passion for something).
And the answer to myself was in the community channels for a given tech. For the most part this was freenode IRC rooms, but sometimes it's Google Groups.
The important thing with approaching people through these channels is not to go in cold or piss them off. But as this should be an area which you know too (or your CTO does, or other devs you have does), then you should open the dialogue in their comfort zone.
Encourage use of the channels and just watch for a bit to see who is giving answers to other people... they're the ones who know what they're doing, and they're the influencers.
Once you know who they are, ask them if they're looking for work, where they're located (timezones help here, if you're in the UK go in early in the morning and you mostly have europeans, and if you're in the US go in late as you mostly have Americans). Even if they're not looking, they may very well know someone in the channel who is looking and they will recommend a good person.
Does this method work? Yes, for me it has done.
Using HN to hire is one example of this (and we found a terrific graduate who started today), and I did the same with the android-dev IRC channel to get a great Android dev. I've also done the same with hiring a great devops guy (another IRC channel).
Basically... if you can't find them, and if you aren't doing things like airbnb (great hiring pages that go viral), red gate (giving away ipads for good interview candidates), then spend your time and effort to go where they go.
I wouldn't call this clever. It's just very basic head-hunting. But frankly that's what you're doing. Stop expecting that the good guys are out there looking for you, they're busy doing stuff... the average guys are out there looking for you.