A popular form of communication in a lot of forums is a diary or blog forum in which members of the site can start their own "blog" or diary. One's blog is basically just a forum thread in this dedicated forum. The idea is that you can keep, for an example, a training/practice diary in a special thread. Obviously, others can comment on the thread. It's just a dedicated place for you to keep notes whatever badminton-related you want. This saves you from having to set up a separate blog on some blog service (for example blogspot.com) if you feel like you don't have that relevant stuff to talk about. A forum thread is a much lighter format and you don't have to worry whether the content is "serious" enough. I don't know if there's a more general demand for such service, but I've seen this idea adopted on many forums and it's been quite successful. I for one would be interested in keeping such a diary. I have a separate blog, but it's in Finnish and for an English blog, a forum blog/thread would suite my needs just perfectly.
Hey, I start my own blog. But it is not about coaching. Just to share interest in the field. http://shuttlerforever.blogspot.com/