Meetup.com works ok, but chamber of commerce i find is better because its generally better suited to businesses. Best thing though is to find trade events, whether its conferences or networking events, product launches, whatever. Pick an industry, lets say, car salesmen. Google for Car salesman trade forums, boom, loads of communities there, generally they have events pages, awards shows, etc, create a calendar and start going. Took hardly any time at all. Apply to any industry.