Maps are a staple of fantasy literature. They’re found in most “traditional” fantasy novels, and those gigantic doorstopper fantasy epics they publish nowadays almost invariably have them — sometimes more than one. Here’s a great cartographic discussion of some of the classic maps of fantasy worlds (Tolkien’s Middle Earth, Oz, Discworld, whatever the continent found in the Wheel of Time series is called, etc.)
[Note: this is a nice companion piece to an earlier post I did on the work of academic Core Olsen, who analyzes the Lord of the Rings.]
Also, here’s a very neat and lengthy piece on an effort to map Marion Zimmer Bradley’s Darkover that I discovered in a comment on the cartography article.