I've got the basic tank warrior in my upper left slot. Shields and maces, armor and athletics, etc.
In my upper right slot I have a lizardman with almost all of his points spent in unarmed. He wears very little armor and has high evasiveness. He's my main damage dealer and he's incredibly good at it.
In my lower left, I have a rouge with my most of her points in Assassination and Daggers. Mostly as a back row DPS, though I always have her equipped with throwing knives in case I feel like doing a bit of ranged damaged without involving my mage.
My lower right is my mage. She's pretty much all ice magic, with a few points spent in Spellcrafting to allow her to equip the first staff you come across. I find I'm enjoying ice magic's ability to deal damage to multiple targets sooner than other schools, at the tradeoff of having to spend more points in it early on to make it really effective.