I would be really interested in hearing success stories about finding cofounders online. I agree that a tight founder/cofounder relationship is tough to find, but there seems to be no shortage of good hackers out there wanting to work on exciting things. So maybe its just a matter of finding one of those hackers that you can get along with? Furthermore, I think the "tightness" of these types of relationships are basically proportional to how good of friends these two people would be outside of that founder/cofounder relationship. I always thought the best teams consisted of best friends.
Like I said, I exhausted my personal networks. Think of it as match.com when all else fails.
Thought I'd add: I currently have two options - continue executing on an idea by myself and hope I'll find someone soon (as a result of the execution) or find someone first and then execute. Which would you pick?
In my experience, searching aggressively for a co-founder is not very good. You might find someone and they will probably have all sorts of issues (e.g. unmotivated, lacking in skills).
Just start building and if you find someone who is interested bring them on board. There are more followers than leaders, be a leader, execute and when you have something cool people will follow.
People are more likely to think your ideas are worthy if they can see it rather than you just explaining it anyway and therefore you have higher chances that they will want to join you.
I would never wait for someone to begin executing on an idea, the search could be very long and hard.
If you can get things up and running perhaps you could take a few early employees on and not need a cofounder.
I actually was in that situation a few years back - I was working on various ideas but nobody I knew had enough interest to give it a full effort. So, I worked a little bit with a few people, but mostly alone, and built stuff.
Then I got lucky and reconnected with someone I went to university with things seemed to click pretty well.
(yes, that does sound strangely close to a 'how we met' story at a wedding...)
I think in those cases the problem, really, is that your personal network isn't large enough. You'll need a large one as a founder, and there will be an overlap between the people that are useful to know and the people that might make potential co-founders.
You should probably be more specific in who you are looking for. Because right now, it looks like you are looking for someone with a pulse.
At least point out some of the skills you are looking for or state if you are looking for someone who can code or someone who is a "business guy with an idea"
You graduated from UT-Austin the same year I did, but I got my degree in Electrical Engineering. I'm still in Austin though and it sounds like you live in Seattle.
Really - a cofounder is a tight relationship that is tough to find. I wouldn't jump into bed with a stranger :)