I just picked up a great way to thank commenters, it was something I would never have known myself if it wasn´t for the great blog of Dawud Miracle. I just installed the plugin that he recommended for wordpress in this post and hopefully it will work for me as well.
I am not going to go into any details here, you can read all you need to know about it at Dawud´s blog. The only thing I am going to say is that it´s something all the people commenting on your blog will really appreciate, and if they appreciate it, they will be coming back to you. In the end it means more traffic to your blog, so it means that everybody will gain from this.
Thank you Dawud!