Philatelic Babirusa (my winning entry in a Googlewhack competition on another board)
From the world of primates:
Douroucouli
Uakari
Slow Loris
Aye-Aye Captain
And the one I’ve suggested once and will continue to recommend in any thread started by a solicitor of a username: Goa Ska Lice, a respacing of the letters in the phrase Go Ask Alice
Maybe it’s a reference to Virginia State Medical Examiner Kay Scarpetta in all those Cornwell novels.
How 'bout:
Fletcher Bowman
Luke Uppindaskye
Condo Leaser Ice
Princess Ownname
Moe Mailliard (Mow My Yard)
Pam B. Namby
Baron Unashamed
Aladdin Sweatpants
Sue Ann Wynn
Claude Baddely
Roxanne Sand
Tucker Inlate
Wagner Tailfeather
Comma Eight Comma One
Killer Snowman
Liquid Nitrogen
Tanooki Suit
Powdered Toast Man
Half Vast
Except for a couple of very obvious ones, and a few explained, most are not making much sense to me. Explanations for why you think your proposals are cool or clever or original would be welcome.
OK,
Comma Eight Comma One - come command code from the Commodore 64
Killer Snowman - Mostly a reference to Calvin & Hobbes
Liquid Nitrogen - duh
Tanooki Suit - Coolest Mario power-up ever
Powdered Toast Man - a character from Ren & Stimpy
Man of the Peephole
Botanists/ Horticulturalists might use one of my two favorite plant names:
Bastard Toadflax
Hoary Puccoon
Sheriff Ishot
C Ash
Flancrest Enterprises
Why not change yours to Cool Username Not Taken? 
Birefringence
Don’t know if you meant me, but I chose A Jerk because of the rule “Don’t be a jerk.” Seemed humorous at the time, but I concede that my humor meter is not the standard.
Because then it would be taken.
Yeah, that was fairly self explanatory. I wonder if they would allow it. Ditto for Troll, Sock, or anything to that effect.
Sir Nigel Dorking
McLovin
Did someone ever take Chicken of Bristol?
For someone with a martyr complex, nothing would work better than posting here under the name of Ignorance. I’ve had thoughts of it a few times, but just because I’m a goofball.
Evol Shandor, the mysterious architect from Ghostbusters.
Awhile back I started threads on cool, never-used Tolkien and Monty Python usernames; there were some great ones there. Nowadays, if I were a Doper noob, I might go for:
Duke of Fraestead - my AD&D character, long ago
Paladin - which he was
Magistrate - my current gig
Chief Justice - my dream job
Buckeye - I’m a proud Ohioan
Obie - and a proud Oberlin graduate
Jethro Q. Walrustitty - one of my all-time favorite Python silly names
H.M. Minister of Silly Walks - from one of my favorite Python sketches
Wensleydale - from both Python and Wallace & Gromit
Stinking Bishop - also from W&G
Annatar - Sauron’s Elvish name as the deceptive “giver of gifts”
His Majesty - to fit my ego, heh
Imhotep Box - the actual name of a person who appeared in court before me
Daphne Threat Medley - ditto, but I’m a dude, so that would be too confusing…
