I use my .mac address for business and changing it would be major pain...I've had the address for half a dozen years and YES, it's the badge of a veteran.
I love going into my local apple store and during checkout when they ask me if I want my receipt emailed and I say "sure" and give them my .mac account getting the smile with something akin to, "Man, you must go way back!"
I'm too nice to say, "Probably back to when you were still in high school." but then again I'm beginning to edge toward the point of being old enough to be their parent - UGH!