This somewhat interests me too. As an indie reviewer, the popularity of my site increases its value to the authors who are reviewed there. Ironically, authors I review are probably promoting my site more than my reviews are promoting them.
Sometimes I sit down and think about it: should I do more than reviews, should I bring on another reviewer to increase output, should I be spreading myself all over cyberspace with Twitter and Facebook and others, set up email alerts for those who wish to become "members" etc. etc. etc.. And then I sigh and realise that I can't have any kind of life if I'm going to make this site really successful, and this site isn't even intended to generate income (or at least, not currently).
Sorry - it's slightly off-topic, but I just wanted to mention that bloggers and reviewers have similar issues to authors when it comes to marketing and social media.
And if you're wondering, it's probably not the best idea to hire me as your campaign manager.
