I very much doubt that many on here know my real name as I don't use it much on internet forums (although I do use it occasionally). I always address or refer to other people by their username unless they specify their real name in their siggy or somewhere like that. I sometimes think that using real names that others don't know can exclude newbies and make them feel as though they are intruding in a personal conversation, although I'm not personally bothered by it.
On another forum I used a fake name as my username then over a period of a couple of years a few of us got to know each other quite well and decided to meet up. When I told everyone my real name they just couldn't get used to calling me something different so continued to use the name I'd adopted online
Same went for another person. Her user name seems to fit her so much better than her real name!
For the record, my real name is Susanne.