There are number of posters who have good screen names, although the two do not go hand in hand
My favourite screen name is BeerandPoker. Simple, straight forward and something most of us relate to.
There are a number of "cute" screen names like RBC or ShawnFannings......but they are trying too hard imo.
And yes, limitles is deep, ironic and funny but still......BeerandPoker takes the cake
btw, I am excluding Witteles because he just got back from Hawaii and a San Diego spa.