After my first day of caching (8 finds!), I sat down to log them and 
realized I needed a login ID. I hadn't given the subject ANY thought, 
but I was itchin' to log my success for the day and had to act quickly.
My (camping, mountain biking & rock climbing) buddies and I had a 
running joke amongst ourselves where we would claim to be the 'meister' 
of whatever we were discussing, as in "I am the ________MEISTER!".
I guess I was sitting there, pumped up by my perceived success for the 
day (Hey! Eight finds in a day is STILL a pretty good total for me), and 
exclaimed "I am the CACHEMEISTER!"
A bit presumptuous and cocky perhaps, but why not?
Of course 'cachemeister' was taken (by a team that still has ZERO 
finds). As with so many other teams, adding  the AZ seemed an easy and 
natural remedy.

Now I'm a legend in my own mind! :-P
Steve, aka AZcachemeister