I've not published as such yet, so don't know if I "count", but for my serial novel I have found that I get heaps of visitors from just posting an announcement (on the same thread of course) on here in the Author Promotions section.
I also post the same announcement on kindleboards, but the response is tiny in comparison to mobileread.
I've built up an email list that also goes out when every episode is done, and its just for those who have signed up on my website, so almost guaranteed to be people into the series. I'm also always asking anyone on the list to pass the episodes on to their friends if they like it.
I just think you are better off posting to a few hundred who you know like your writing, rather than a few thousand who never heard of you. (maybe both would be better?)
Small steps