Mostly I just hang out here at 20sb. It's the best blog network I've found by far. Otherwise, I read and comment on other people's blogs and chat with them on twitter.
I comment on blogs, use twitter, post on forums with link in my signature and if relevant link in posts, participate in link exchanges with blogs of a similar theme, I use ping.fm to update my status on facebook, myspace, bebo and twitter whenever I post on my blog (twitterfeed notifies ping.fm when it reads the rss feed), and I use communities like 20sb.
I make my husband wear a sandwich board that says, "Read The Pilgrim Congress Or My Wife Will Beat Me" on the front, and "No, Really. I'm Totally Serious. Pilgrim Congress."
I second what Writing to Reach You has said. 20SB totally rocks. I've met a small handful of some of these bloggers in person, and am continuing to connect with people online too... and they do indeed totally rock.
I've got my blog listed in some different networks, it's on Facebook's Networked Blogs, it's on BlogHer, it's on a few other places... but really being on 20SB has been the best as far as getting more readers as well as making new friends along the way. I think only twitter really competes with how I get people over to my blog, but I feel that most people find my twitter through some connection to 20SB...
I also want to say that I bought mini business cards for my blog too, so I can hand them out to people I meet because inevitably my blog will come up at some point. :)
I went with a cheaper option, and they aren't bad at all... but I do know that moo.com is pretty awesome when it comes to these mini cards. I don't even remember who I went with... 1(something)1, that's all I remember... but they were under $10 for 250, double sided (though the back is in black and white).... shipping was like $10 too.