Funny this topic should come up.  A couple of weeks ago I got a very nasty email from the guy on ebay selling the Skylark for more than the new price.  He asked me how I ever got into his country with a name like lbpesq, told me that I had no right to be in North America, should go back to my own country, and threatened to make me his wife!
 
Anyway lbp stands for Little Billy Panzer.  In the late 60's my older brother (by 5 1/2 years) and his college roommate used to have fun getting Dave's little brother (me) stoned.  In '73, when I moved to California right out of High School, the roommate was the only guy I knew living in California, having moved out a couple of years earlier.  He told his friends that Little Billy was coming out.  When I showed up, having grown to 6'2 in the ensuing years and now a head taller than the roommate, everyone was surprised and the Little Billy moniker stuck, later shortened to LBP.  The esq part is for esquire, as in attorney.
 
Bill, tgo

Lidon is a name I'd use for dungeon type computer games, a play off of Johnny Lydon of the Sex Pistols.  I added the 2001 for my user name at the BBS Compuserve because then the year was a long way off.
 
T

No comment if you know what my first name is!
 
Oh ...
 
that other name?
 
That P-T-B-O-thing?
 
Probably the longest running gag in this club!
 
Paul the bad one

Mine's an acronym.

Serialnumber12,,,,,,simply speaks for My bass .....although my name is keavin...(pronounced kevin).

Serialnumber12,,,,,,simply speaks for My Bass .....although my name is keavin...(pronounced kevin).

Precarius is a Latin word that means to depend upon Grace. The word prayer comes from the Latin root precarius. Most people just think I don't spell very well.

Mine is a very cleverly constructed palindrome.

b-o-b; b-o-b; hey, you're right!

Mine's obvious, but it was bestowed on me by non deadheads I know.  I accepted the name with pleasure, much to their disgust!
 
Mark

Mike, now thats too cool. PRECARIUS, so far my favorite username origin.

Z for Zimmerman
 
Superdog- Love my dogs

although davr35 is a version of my name davr=Dave Renois it is original because 35 was my age at the time I came up with it

One has only so much creativity to spend, right? Why spend it on screen aliases.
 
Well alright, all you guys win!

Well, here's a quote from Wikipedia-
 
In Norse mythology, Yggdrasil is the World Tree, a gigantic ash tree, thought to connect all the nine worlds of Norse cosmology.  
Wikipedia Yggdrasil Entry  
 
Since the highest percentage of my ancestors are Icelandic, this,combined with Jack Casady being credited with Yggdrasil Bass on the Airplane's Crown of Creation (would've been an Alembicized Guild Starfire)led to my handle.
 
It's also the personalized plate on the Jefferson Campervan, leading to an amusing parade of perplexed passers-by pondering just what the hell kind of acronym that is! :-)