I've really gotten into twitter in the past couple of months after having an account for several years and doing nothing with it. Once I started adding people to follow it started to get a lot more interesting and then I found that other writers hang out on there and people blog about writing, how to do it better, how to publish a book, how to find an agent etc. Even some agents blog and twitter and you can learn from them too.
There is also the self-publishing crowd, and there is lots of advice on how to do it and why you should or shouldn't do it. There still seems to be a bit of stigma attached to self-publishing because so much drek is making it on Amazon and other sites for easy download. Some of these are obvious by the crappy book covers or poorly written descriptions, but some of it sneaks under the RADAR and clogs up the path for really good books. I'm still torn about self-publishing. You have a lot more control over timing and price-points and book covers etc. You lose out in marketing and the "Cheese-touch" of self-publishing. All of these things are side issues to actually finishing the novel though.