It doesn't look like any of the answers given have actually answered the question you posed -- so I'll do my best:

The best place to look is within your OWN personal networks. At the end of the day, a co-founder is very similar to having a husband or wife. Your life will be tied to this person in almost every conceivable way. In fact, you may even spend twice as much time with this person than your actual husband or wife (if you have one). For that reason, it's important that the level of trust you have in this person is second-to-none.

Finding co-founders at networking events, local universities, etc is fine -- however, be sure to spend a lot of time with this person before you decide to bring them on board as a co-founder. Starting the conversation off saying "I'm looking for a co-founder" is similar to meeting a girl and saying "I'm looking for a wife."

But, again, this is why your own personal networks might be the answer. It's likely that in this group of people, you'll find people you trust who will be in your startup with you throughout the good and the bad (because, yes...there will be good and bad).

I hope this is helpful...

One of my favorite answers to this question by my friend Andrew Peek ( http://twitter.com/drupeek ):
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I've written this post in response to the assertion that a business/product person trying to find a technical co-founder is next to impossible. If this is your issue, I feel compelled to preface this post by saying: There are much bigger hurdles ahead.

Maybe I lucked out. Maybe it doesn't scale. Regardless, here is what I did...

First - Get into the middle of the circle. Stop standing on the perimeter.
Show up at technical events – ask what you think are stupid questions. Don’t try and memorize database types and programming languages – just work to understand the variables at play and the frameworks for making technical decisions. When do you need a Document Database? When do you need to layer an indexing engine? What languages have strong developement communities? How much work is involved in porting an app after 1 year? 2 years? Ask someone about code debt.

Second - Go where the smart people are. Shut up and listen.
I read Hacker News everyday. I pay attention to who posts, who comments and who I find myself nodding along with or, at least, respectfully disagreeing with. Sure, this isn’t a perfect representation of the offline world, but it’s a pretty cultivated community. Did you know that Hacker News has a google spreadsheet of contractors and also a list of co-founders seeking co-founders?

Whatever you do – don’t go messing it up for the people there currently. You can listen, but if you’re going to contribute, raise your personal filter two full orders of magnitude. My HN account is 1322 days old (Paul Graham’s is 1490), but I’ve only ever made 3 submissions. [I suppose it's equally likely that I'm either a very good listener, or an overly timid non-contributor.]

Third - Look for a curious mind.
I’m big on curiosity. Curious people enjoy exploring and solving problems. The people that immediately rose to the top of my list had spent hours experimenting with problems that were tangential, or related to the crux of my idea (this post is not about the app). If you’ve never explored a github account, you should probably get acquainted. What are you looking for on github? Contributions. What languages/libraries are they contributing to, or watching? Is there a pattern? Do they have a personal website that hosts their projects as well? A stackoverflow account?

Fourth - Meet in person.
Two reasons: a) if they’re not up for a one hour coffee, they won’t be up for the thralls of a startup, and b) you’ll never successfully explain your bigger picture by email. You also need to be able to articulate your bigger picture in a competent manner. Don’t go in guns-a-blazin’ about how you plan on de-throning Google or Facebook. You need to strategically demonstrate your ability to roadmap, your market entry wedge, and how you intend to position the product against a specific customer. I met a dozen developers in my search, all of whom wanted to know, “what’s the use case?” Make sure you have one – they’ve seen what happens when you don’t.

Fifth - Convince somebody first.
It helps if you’ve convinced someone (anyone) beforehand. I was lucky – I had the Jet Cooper team behind me. That was huge. It added a legitimate design arm and enough of a runway for me to prove or disprove the merits of the idea. I had also assembled a technically exceptional Advisory Board from places like the University of Toronto’s CS Dept., Mozilla, and a highly regarded Toronto startup. Each advisor brought a specific technical expertise to the table and could support my co-founder on everything from building out the API and its ecosystem, to managing scale. Most importantly, these advisors were doing this as a labour of love. They believed in the idea and were curious minds themselves.

Sixth - Start small. You are, after all, strangers.
Pay them. With money. Decide on an objective and get out your cheque book. Nothing speaks louder than you having your own skin in the game.

Total credit goes to the person this post is about (my co-founder in the making). It was their idea. I had a plan to release a public beta 90 days after we began writing code. They countered with 30 days to build a product that could be released to a select group of beta-testers in a controlled, watchful environment. We were getting along already. This person had challenged my ability to strip away scope and test the core hypothesis. In doing so, they had created a sprint-like environment from which we would emerge either as co-founders, or utterly sick of each other.

This is also great way to uncover everyone’s tolerance for risk. Some people can throw all caution to the wind off of one good observation – others need to see a couple variables played out before mortgaging their future.

Seventh (Bonus) - Look for the ‘X’ factor.
The fact that I’m not technically trained has always pushed me to work a little harder. It’s like this challenge I carry with me in my back pocket. When I met Jen, she was this incredibly curious and intelligent person. She knew what she knew, but could put aside her ego if the situation required it. I love that about her. We share the desire to produce the best possible product (as does the rest of the Jet Cooper team) – regardless of whose feelings get hurt. And while I can’t speak for Jen, I have to imagine that being a woman in tech also comes with a little extra motivation too.

So there you have it. A less little difficult than previously imagined.

If you’re trying to start a startup and you can’t code yourself out of a paper bag, drop me a line and I’d be happy to help where I can.

http://www.jetcooper.com/blog/how-to-find-a-technical-co-founder/

It's likely that based on your question, you're not yet ready to find the right person because you haven't defined clearly enough who you're looking for and how they fit into your company.

Mike's answer is great and answers the question most directly. I would add that what you're really looking for is someone that knows you well and knows a potential candidate well enough to feel comfortable making the introduction and endorsement of both parties. As Mike points out, a co-founder is similar to a marriage and one where personal chemistry is the most important test to determine potential for a lasting and meaningful relationship.

But your question detail has me wondering why you're looking for a technical co-founder if - as you say - you're looking for redundancy? If you're strong technically, why not hire a Sr Engineering Manager or Product Manager or even Director of Engineering? All of these would likely be single percentage equity hires vs a double-digit co-founder.

So again, get really clear on what you're looking for (the attributes that add to your existing bench strength), why you're looking for that person (how you see their responsibilities interacting with the responsibilities of others in your org, especially yourself), and what the right fit is going to "feel like" (i.e. culture fit definition).

Once you can articulate these things clearly, it'll be easier to find that perfect candidate.

Happy to talk to you about any of this in more detail in a call.

Hi. I have to agree with Mike. I had a technology business that developed an unbreakable encryption product for internet payments and software anti-piracy, and when I needed a qualified tech co-founder, I looked within my own network. After doing some due diligence, I actually ended up asking my lead developer. This worked on several levels: We already had a great relationship built on the time we worked together. We had similar beliefs but he wasn't a 'yes' man. He also complemented my strengths and filled in the gaps where I was lacking. I always hire people smarter than me so I can continually learn and grow. The company as a whole grows too. Hope that helps!

Great question and the first focus is not to hire a person that has the same talents as you. That's a killer in business partnerships...a recipe for failure. Next...they need to share your vision of where you want the company to go. And thirdly..why do they have to be a geek with some business knowledge. One of the most successful guys in the tech world is NB's Gerry Pond...his educational background? DEgree in psychology. Remember you are building a team...each one of you needs to compliment the other including leadership.

You have your priorities backward. You need an experienced business person with some tech knowledge. A smart person can learn what he or she needs to learn about your business fairly quickly. The chances of you getting hit by a bus are smaller than your need for business experience in the C-suite.

I agree, one should try to keep the talent overlap to a minimum. It's a startup, there are uncertainties and risks involved. Try to keep the team lean and diverse.

On a side note: For self development, I am volunteer helping out companies in tech/dev so if you have something interesting, I may not mind helping you.

Find technical events on meetup.com and see who is good.

Startup Digest also has listings for every city. Subscribe and go the edgy stuff.

One of the best ways is also join programmers in hackathons or startup weekend. You should enquire for the list of attendees before the event and message, and see if there's any fit. A weekend working on an app is like doing a mini startup.

Of course, you should have a solid web page somewhere showing what you want to build -- otherwise it's a hard sell for programmers