CommentLuv is a great wordpress plugin which enables you to reward your blog readers by leaving a titled link to their last post automatically whenever they comment thus encouraging more comments. It currently runs as a WordPress or Drupal plugin. You can take advantage of the extended features of CommentLuv by registering your URL at www.commentluv.com. Use the register link below to choose your username and once activated, you’ll be able to see top 20 active sites and see which of your last blog post links have been clicked.
I just register commentluv.com and looking forward to use Gravatar.