Look at the Memberlist
there are lots of registered users but inactive for a long period of time... you can post and read a thread without getting yourself a username. I wonder what's the purpose of registering yourself a username in the forum and after all you don't use it?
I live and work in Asia, where we get a lot of users who register but never post. Most of them come out of Russia. My guess is that they are using the forum to send PMs to each other, possibly so that they cannot be monitored so easily by government watchdogs. Also, registering at many forums and posting your url is a good way to get more traffic. But this only works well if people are looking through the member list and following links. For example, you can go to the many free blogs out there and sign up and make a single entry about your forum. It takes a little time, but inevitably will bring more traffic your way, even if you never go back to that blog.
It brings up the question, what really is spam? Spam is like weeds. The definition of a weed is something you don't want growing somewhere. The most beautiful flowers in the world can be called weeds, if they are growing in your driveway and breaking up the pavement. Some forums don't mind people self-promoting, as long as it doesn't get in the way. I am a little concerned about so many people never posting on my forum and taking up my resources, but so far it isn't a problem and makes my forum look a lot more active (although not really active at all!)
Also, I got a huge inactive list. Sometimes one of those people actually registers later on, because maybe they didn't check their email in a while and didn't see the activation email your forum sent to them. So I'm a little slow to delete inactive users. But the list is growing, fast. Stay tuned and find out how the story ends... EDITED by Eenie:I disabled your sig since it spams another site in it which is against our Forum AUP.
Also, do you realize that this thread has been inactive for over 4 years?