Mostly just this: http://melbourne.twitterusergroup.com/ though I imagine attending things like StartupCamps would also be beneficial.

Letting people know is as simple as putting it in your introduction when you first meet. "So what do you do again?" "I'm a freelance web developer actually, at the moment I'm working on X but I do a lot of different stuff including Y and Z." There's no need to go overboard on 'selling yourself', if people like you and know what you do that's enough.