Oh forgot to mention. In the book Magician, they were fighting people from another world right? Well the guy who wrote magician has co-wrote with a woman another series based on the world from which the fighters came from. I have the books in storage so cant give you exact details, but I think there are 3 of them, starting with Daughter of the Empire. I REALLY enjoyed these books. Worth a try.

Sally-Yes I agree, nothing more annoying than not having a completed series to read. I too have had a little part when I have seen certain books, much to my mums amusement.