Ask HN: How do you meet like minded/purposeful people?

I've got a number of 'good ideas' going on the side - like most I imagine. Most skills I didn't have to start work on these ideas I've tried to learn and develop. There are just some things I can't learn or do.

How do you go about meeting people who are interested in helping others develop ideas? Google+ seems to be great starting point but are there places dedicated to bringing smart people together? Say, you want to speak to a front end developer or a database engineer? Outside your friends circle, where would go looking?

The StackExchange sites are a good example but are rather formal and text bound.