An interesting Quora thread on the topic. Yishan Wong's answer (below) is well-worth the read (although we don't fully agree with his first point of course!). Check out the rest of the answers here:
- Do not rely on your HR staff to source top-tier engineers for you. They are good at sourcing mediocre programmers; the 10x engineers are typically not accessible to them, nor are they able to properly identify one when they come across them by accident. They are no better at doing this than you are at being able to identify top-tier HR professionals. (Note: your HR group is extremely vital in handling interview logistics, negotiating offers, closing candidates, and onboarding them, so don't go neglecting your HR folks!)
- Look to referrals of referrals. Look for the best person according to the best person according to the best person you know (yes, that's two levels). If there is consensus among several of your best people, this is a fairly reliable indicator. It is difficult to go more than 3x per "link" though - people are typically unable to discern the difference between someone 9x as good as they are from someone who is 3x as good as they are; this is why you have to do the "best person you know" referral twice. First, you hire all the best people you know, work with them for awhile to find the best amongst them, and then find all the best people they know. It is a multiple-stage approach; many people don't know this, and just assume that "refer the best people you know" is the end of it.
- Don't look on job boards. Top-tier candidates are never looking for a job. Anyone you find who is looking for a job is very likely to be mediocre or worse - companies lay people off starting at the bottom of the performance ladder, so the pool of people looking for a job is skewed downwards, and be aware that many of these people may still have impressive-looking resumes. There are very occasional exceptions (e.g. someone moving because their spouse got a job, fresh college grads, etc.) but as a pure numbers game you are unlikely to run into them and you can usually access those people via networks of referrals anyhow.
- Attract them to you. It's hard to dig them out, so get them to come to you. If you have enough of a public presence (i.e. you are not a secret stealth startup), you can do things publicly to attract top-tier candidates. Create an environment that intrigues exceptional people, issue public challenges (Facebook did puzzles primarily to flush self-starting problem-solvers out of the woodwork), and put out a call in public forums in an argot or referencing things that only top-tier people would recognize or care about.
- When interviewing, ensure a positive candidate experience, even if the candidate is obnoxiously terrible. The impression you want to give every single candidate is "Wow, this is a great place to work! The people are really nice, even if I didn't make the cut!" If you reject them, so long as they still have a glowing impression of you, they may very well refer their smarter friend to you (their motivation being to live vicariously through that person successfully getting a job with you). Subsequent candidates who come through referrals of failed candidates are still a good bet to examine.
- Looking at past accomplishments is useful, but there are pitfalls. 10x people usually have a record of accomplishment, even at the beginning of their careers. However, sometimes environment is a strong determinant, and it's important to examine closely how that person contributed directly to that accomplishment, especially if they worked as part of a team (if they were part of an all-star accomplishment but weren't primarily responsible, don't get discouraged - you are now only one hop away from whoever was responsible!) Also, some people may be done achieving: after a string of world-class achievements, they may have given all they can give and aren't on fire any more. Make sure they've still got motivation and hunger for the future!
- Lastly: intelligence and talent only make up part of the equation. Someone with an overwhelming amount of drive and the ability to finish projects is much more likely to be productive. You can place them in an environment with smarter people and great ideas, and they will be the catalysts or prime movers to turn all those ideas into reality. Top-tier engineers don't always have all their brilliant ideas on their own - they are typically productive because they can take ideas and make them real.