IMHO, the best way to find like minded co-founders is to actively attend meetups, hackathons, conferences and related events. You will be surprised how often you will find passionate people who are very much willing to work and join forces with people like you.
We agree that offline methods are very important to the co-founder search too. In addition to an online matching platform at CoFoundersLab.com, CoFoundersLab holds quarterly Matchups events in many cities (via Meetup) to facilitate some of the "in-person dating" for founders: http://www.cofounderslab.com/entrepreneurs-meetup-networking
