We have seen a number of teams form or add co-founders as a result of discussions at or introductions from a conversation at a Bootstrappers Breakfast. The small group setting (8-16 folks around a table) doesn’t put introverts at as much of a disadvantage as having to speak to a group of 30-100 does. One facilitated conversation means that everyone gets a chance to be heard and to contribute, and the networking takes place after the event when everyone has some context from the prior discussion to be able to start a conversation.
While our primary purpose is to help entrepreneurs compare notes on common challenges related to organic growth, we have seen that these same discussions also foster a number of co-founder discussions and introductions. If you attend a breakfast in Silicon Valley we will allow you to post a brief (100-150 words) description of your startup and what you are looking for in a co-founder to our newsletter that is sent out to about 800 bootstrappers. There are a number of events in Silicon Valley that support co-founder matching in different ways: each has a different format that has its own strengths and weaknesses:
There is an even longer list of on-line only sites but I haven’t personally heard of much success from that approach. I think it’s because there is something about a face to face conversation–it communicates an order of magnitude more information that’s private and directed–that makes it hard to replicate on-line. See also last year’s “Round Up Of Co-Founding Events“