People have always been fascinated with investigating their home--the Earth. For centuries, maps have stirred imaginations and inspired explorations of the unknown. Maps are a rich source of information, showing spatial relationships between climate, vegetation, population, landforms, river systems, land use, soils, natural hazards, and much more. With them everybody can examine the "whys of where"--the essence of scientific and geographic inquiry. But maps aren't just confined to learning about geography. Imagine an epidemiologist studying the spread of diseases, a scientist studying climate change, or a businessperson determining where to site a new retail establishment. In each case, maps are critical tools for studying these issues and for solving real problems. Furthermore, as rich as paper maps are, they are limited because the Earth is constantly changing. With the advent of today's geotechnologies, such as Web mapping services and Geographic Information Systems (GIS), the teacher, librarian, and student can analyze diverse phenomena--from population distribution to biomes as they change. But determining which resources and tools are most valuable for the classroom can be confusing. This article focuses on a few excellent places to start, and ideas on how to use these resources in the classroom. (Contains 11 figures.)