Well, you can't forget St. Feuillien, Hoegaarden (the dark stuff is good, white is ick, imo), Orval, Petrus, De Koninck, Delirium Tremens, Orbier... hrmm.. to name a few. Forgive me if I mis-spelt any of these names.
Belgian beer is really good stuff. A lot of their beer comes from abbeys...