I suggest you take a look at A Landscape With Dragons: The Battle for Your Child's Mind by Michael O'Brien. Interestingly, Amazon also lists Landscape With Dragons; Christian and Pagan Imagination in Children's Literature, by the same author. It seems that only the first one has descriptive text accompanying it on Amazon. I have not read either one myself, but O'Brien is supposed to list recommended works of fantasy. I'm sure the list is in the first book, I don't know about the second.
You may also be interested in Christian Mythmakers : C. S. Lewis, Madeleine L'Engle, J. R. R. Tolkien, George MacDonald, G. K. Chesterton & Others by Rolland Hein. I have also not read this, but I saw it in Borders once, and it appears to be an overview of well-known Christian fantasy authors.
It would be best if I were recommending sources with which I am personally familiar, but I thought you might find the suggestions helpful.
You might also want to review the article Good Fantasy & Bad Fantasy from the evangelical Christian Research Institute.
For instance, I read Harry Potter, Susan Cooper's Dark is Rising, and Ursula LeGuin's Earthsea, all of which have been condemned by some Christians I know. On the other hand I myself think certain series (Donaldson's Thomas Covenant, Pullman's His Dark Materials) are completely unsuitable for Christian children, and maybe even for adults. I know Christians who read Stephen King and Anne Rice, and others who ban Mary Poppins from their homes. Everyone must strike his own balance.
Heck, if I attended a Christian college I'd probably be hauled off and burned with my own books; I read stuff by atheists, Buddhists, pagans and weirdoes. I think there's a definite difference between "bad becase it's not Christian" and "bad because it attacks Christianity". Oh, let's ditch this conversation and read Tolkien... at least until the "Tolkien was an evil idolater" people show up!
-ksen