Just another thought on Twitter: I've been tweeting about various subjects, and it's clear by the followers I'm getting that they often come via searches for certain keywords.
For instance, early on I tweeted about UFOs, and sure enough got a follower whose site was dedicated to the subject of sightings of alien space ships. Recently I mentioned the term "dating sites" in a tweet, and soon had a follower who was tweeting about these and nothing else. Of course, there's no point in following these guys. And they'll unfollow me in time anyway, when they realize I'm not in their niche.
My Twitter page is really eclectic, so this is going to happen from time to time. Still, through this process I'll eventually bring in followers who are interested in the same range of subjects I am. So, it's a good lesson. Just as with blogging, it's always worth including popular search terms and keywords.