I'm finding that StumbleUpon has been the most effective social button on the site. I've been consistently sharing my blog entires on StumbleUpon and other content sharing sites like Digg, Reddit, Twitter, Linkedin, +1, Facebook, and maybe a couple other ones. It's mostly a waste of time except for StumbleUpon.
I get almost nothing with the other buttons, but StumbleUpon can consistently get me hundreds of referrals whenever I write about technology. I get nothing when I write about movie stuff though, which makes me wonder if most of their users are tech geeks (I mean that in a good way).
Maybe not. They have movie fans too. A day after I wrote this, two of my latest blog entries from MoviesWithButter have been stumbleupon-ed.
I guess I shouldn't be surprised by StumbleUpon's effectiveness. I only started submitting to StumbleUpon after reading an article about how it had surpassed Facebook's Share/Like buttons for driving traffic to other websites for that particular month. Since then, its lead over Facebook has widened. According to Mashable, StumbleUpon's 12M users drives 10% more traffic to other sites than Facebook's 750M users. Impressive.