3-D Starmaps: Lots of data and links for real space stars and star mapping in general.
Fantasy Mapmaking 101: Map making is an art form dating back into the depths of time. Before there were GPS' (global positioning satellites), there were maps. It took a skilled mathematician and artist to create a precise map, and sailors and navigators around the world relied on exact accuracy. Maps can be symbolic, imaginary, or just plain useful.
Gozzy's Cartographic Emporium: Maps for use with tabletop fantasy roleplaying games.
Lankhmar Geomorphs: Geomorphs for mapping city areas, available in Campaign Cartographer or GIF format.
Maps: Real Maps and Building Plans. A short article with links from the Vesanto Worldbuilding site.
Peter's Guide to Map Creation: Advice about how to draw fantasy maps, with links.