I have seen quite a few good one over my years, but I forget them all.
So, I will go with my second Alias:
Pointyfern
"The pointiest fern around"
I actually got that name randomly generated when i first signed up for Halo, and I now use it not only for Xbox Live, but also Soldier of Fortune II, and my WC3 account I play on when not playing WotE.
I saw DeadthKnight and thought it was supposed to be Dead Thehelper Knight but it was just DeathKnight with a d so it is like dead.
My favorite account names are, ArmedCivilian, ArmedCitizen, and Mon-E. All my account names. (Of course you would use your favorite name for yourself. )
Ghan has said he has fixed this. Monovertex please confirm this fix. This was only a problem with people that had signatures in the upper levels like not the special members but the respected members.