Normally the smaller stuff. Eg for Python/data science in London there's a meetup.com miniconf that gets hosted in various company offices and you just sign up

Normally the smaller stuff. Eg for Python/data science in London there's a meetup.com miniconf that gets hosted in various company offices and you just sign up and turn up and listen to some cool people talk about whatever mad science they've been up to. Good places to find jobs/people too.