I have been a resident in Second Life since Tue 22nd Mar 2005. I have spent most my time in world learning and trying to say that I specialise in one area gets tricky. I have specilisations within various areas but I have tried my hand at most things I have had a chance at.
My main skill (going on the custom work I am predominately asked about) would be scripting. Within scripting I concentrate on data management. 
My General knowledge of Second Life enable me to fit most roles and I have an ability to optimise the majority of projects/events.