Helpdesk tool of choice for all us geeks

People, a simple question. What is the Helpdesk/ServiceDesk/Solution Center of choice for your businesses? We all use them (for the most part) in one way shape or form. MY dilemma is I've started working at a place which has no such thing at all! Any thoughts/comments are appreciated. (by the way I've used a lot and think they all ..."suck")