I have one, but I don't particularly associate myself with it.
Most of the time it's ever been used, it has been to scold me, you know the "First Middle!" thing...
But really, I don't think about it much.
I primarily associate with my first name, my screen-names, and a few nicknames that pay no respect to me having a middle name.
Not to say I don't like it, I just don't care...lol