[guero]

You may want to try http://www.founder2be.com as an additional tool in your co-founder search.

Note: I co-founded this up after not finding a co-founder for an earlier idea myself. Somehow this idea of building a match.com for co-founder seems to have filled a need and now there are 10,000 or so incl. current and ex- Googlers, Apple, etc.

I love the topic of co-founder finding. Also because some people have surprisingly strong opinions about whether a service like this can be possible at all or if you need to go way back with your co-founder.

As was said earlier, the Dropbox co-founders did not know each other long before... I think anything is possible. It depends on the co-founders ;)