This author goes on to say that you could find these via a search for your keyword - and then finding forums which support (site-linked) comments. Internet Sales and Tips was a linked forum.
Comment Marketing is a great way to obtain top positions on Google for your websites.:
"The fact of the matter is, that comment marketing can obtain some very high search engine rankings on Google! Yes, that is exactly what I said. The simple act of either making a comment to an existing post, or writing a new thread, you have just set yourself up for some great positioning on the search engines.
The key to this process lies in your ability to write good original content. This art of comment marketing could be thought of much the same way that writing press releases, ezine articles and blog posts are. The difference in advertising a product and giving people solutions and alternatives to problems is the huge difference in whether comment marketing works well for you or not. Obviously, if you are a good writer and have moved out of the mentality of advertising your product or service and are able to give people different examples of how your product can assist them with their business, then you will be on the right track."