LinkedIn is probably the most direct. I don't like stack overflow although you get contacted for available jobs, no recruiter spends more than 10secs to watch you profile and see if you remotely match the position. 8 out of 10 that contacted me were about positions that were simply bad the requirements were an total mess ( like that doesn't happen everywhere, but whatever ) and lets just don't get started on the startup culture of every company with an profile on that site.