My favourite books in the whole world are The Age Of The Five Trilogy. I read the first two at great speed, picked up the third [The Voice Of The Gods] and refused to read more than half because I can't bear the fact that the story will be over. There are so many twists and turns, just when you think you know what's happening, everything turns on it's head and leaves you reeling. I cannot say enough about these books. Trudi Canavan's first trilogy was the Black Magician's Trilogy.
The prequel to the initial trilogy came out in 2009, The Magician's Apprentice, although I haven't read it yet as I recently bought the 1st book in her newest trilogy which is the sequel to the Black Magician's Trilogy!! The Traitor Spy Trilogy [as it is known] takes place a generation later than the previous trilogy and the second and third books in this trilogy will be released in 2011 and 2012 respectively. Trudi Canavan is definitely one to watch!!