Er...

• If you call me Brent, you're either a fairly close online friend, or someone I know in real life.
• If you call me Brent-san, you're probably one of Liz's friends.
• If you call me Brent-kun, you're either Rachel or Liz, in a weird mood.
• If you call me Brenton, you're either a teacher on the first day of class, or going to get your ass kicked.
• If you call me Burenton-san, Izumi-sensei desu.
• If you call me Brent Dax, you're probably either in Open Source, or you don't know me that well.
• If you call me Daxster, you're probably the funniest guy I know.
• If you call me Dax, you're an online acquaintance.
• If you call me Lieutenant or Ensign, I'll ask if you've escaped AOHell's clutches yet.
• [edit]If you call me Ensign Expendable, you're about to be sniped right off the holodeck. ph34r my phaser rifle! (I am a shameless sniper when playing Elite Force.)[/edit]
• If you call me Dark, I'll ask if you've taken the red pill yet.
• If you call me BD, I'll get very embarrassed at what you probably saw and change my Kazaa settings.
• If you call me brent or brentdax, you're an instance of bash(1).
• If you call me daddy, you're a cutecute bot-rin.
• If you call me "unsatisfied with 1590 on his SAT", we need to have a talk about your child support payments.

That's it, really. I haven't used many handles in my life, I don't collect family members (bot-rins don't count), and "Brent" doesn't lend itself to nicknames.

Oh, and that last one:
<brentdax> purl, brentdax?
<purl> i guess brentdax is mailto:brentdax@cpan.org or young in a depressingly-better-at-coding-than-I-am kind of way. or an impatient young whippersnapper or unsatisfied with 1590 on his SAT or a slacker