Saw this discussion in the PS3 subforum for PSN names so I thought I'd start one here.
A few I've seen:
FOLLOWMEIAMNOOB (he wasn't a noob)
WWWMMMWWMWWMMW (or something like that - causes some games to glitch because it's so long)
Forty People (so it shows up "You Killed Forty People")
Yorselph (as in Yourself)
Any you've seen?
EDIT: Names like L3g1Tz Sn1PeZz are unoriginal and lame.