Reddit and Stumbleupon is the highest effort to reward sites out there. You can barely get any traffic with Digg if it's not front page, but Reddit do.
Cade, Thanks for your comments. I agree that Reddit is not as pretty and user friendly, which could very well be a reason that it is not as successful as the others. Thanks, Mark
Thanks for you review of Reddit, Mark. Though I'm more of a Digg and Stumbleupon user, I have found the user interface on Reddit, not as appealling as Digg or Stumbleupon. Its probably reason I tend to use the other sites more. In saying that I have had some reasonable traffic come from Reddit, so my readers obviously enjoy the site, and it definitely serves a purpose. I'm enjoy your review of the Social Media Sites, keep up the great work.