okay…after hitting “reply”, I am now aware of my double entendre.
…and I am condoning such an entendre.
Shoemaker-Shoemaker-Levy Nine
or
Lump and Prole
(puppy names, all of them)
Throbbing Member
Cyborg Platypus
My usual name on other boards and whatnot, Shade Edge (synonyms! yay!).
Enseifer from my very short time RPing with a friend. I think it means something in both one of the Tolkein elvish languages and also german, randomly. Also my character name on WoW and CoH.
Tycho Celchu I use sometimes, too.
Candid Gamera 
Jimmy Carter
I’d’ve been Diogenes or Diogenes the Cynic if I hadn’t been beaten to it.
Mind you, the present incumbent deserves it by virtue of being much more cynical than me. (Which is a mark of respect really.)
But the hastily-chosen username has grown on me, and if it wasn’t this, likely enough it would be another oyarsa.
I started out with a boring variation on my actual name, but soon changed it to what you see above (yes, I’m a Tolkien fan). If I changed it again, I’d probably go for a Monty Python-inspired name like:
Jethro Q. Walrustitty, MP
Ole Ftang Ftang Biscuitbarrel, MP
Dinsdale Piranha
Albatross!
Insp. Harry “Snapper” Organs
Arthur “Two Sheds” Jackson
It’s…the Bishop!
Colin Mozart
Ken Clean-Air System
Ken Shabby
The Man from the Off-Licence
Mr. Git
Mr. Dibley
Mr. Neutron
Pantomime Horse
The Poet McTeagle
Scott of the Sahara
Spot the Loony
Johann Gombolputty &tc. von Hautkopf of Ulm
Or something else from Tolkien (some of which I suggested to What Exit? awhile back):
Imladris Denizen
Cirdan the Shipwright
Corsair of Umbar
Shire-Reeve
The Old Took
Olorin
Tharkun
Mithrandir
Elrond’s Long-term Houseguest
Anduril Wielder
A Ranger of Gondor
Dunedain
The Dunedain
Prince of Ithilien
Maybe a law-related username?
Hadley V. Baxendale
Officious Intermeddler
Magistrate
Oyez Oyez
Or something from my AD&D days?
Duke of Fraestead
Paladin
Viceroy
I like my current username, though, and I’m keepin’ it.
If I hadn’t been set on changing to this name, I’d have changed to Tom Veil with “Nowhere, man.” as my location.
This one had me rolling.
I’d probably go with **WAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAALT!!!
**
Oh I forgot: in IM I use guntramboso, in honor of my favorite 6th-century Merovingian, and because I knew it wouldn’t be taken and I was in a hurry when I signed up
I very nearly registered as Pooh d’Etat, a screen name that I used in the old BBS days in the 1980s.
I love it!
I’d really like to change my username to Amythyst. It’s the name that I use on all other message boards, and it means more to me than my current username (it’s a play on my real name and my love of all things purple). But since there’s already an Amethyst on the board, I can’t use it. 
I wish I knew. Something that would make men lust for me: mind, body and soul. Any ideas?
I Put Out?
Hmm, that doesn’t really address the mind and soul part very well…
previous thread on the same topic
As I said there, I think I’d change my name to Australopithecus, because I always liked the way that rolled off the tongue.
The username I’m probably most jealous of is bob_loblaw.
I’d probably become an obscure tenor saxophonist like Armand Camgros, Merrow Bodge, George Snurpus or B. Zoff.
Pamela Anderson, PHD.
In the same vein as DancesWithCats, I saw the name “StandswithaFish” on another message board. I try to be original, so I didn’t want to take it.