Topozone - a wonderful mapping site, with topo mapping capability of the entire US.
Lost Outdoors - Map Maker - a fun map page with some neat extras for GPS hunts.
GPS Visualizer - a free on-line utility that creates SVG (Scalable Vector Graphics) maps and profiles from GPS waypoints and tracks.
Geocoding - change an address or point of interest in any of 22 countries into lat/long coordinates.
USGS Mapping Page - a cool searchable database from the US Geological Survey.
U.S. Gazetteer - a search page that can find lat/long coordinates from keywords.
Maporama - a mapping program much like topozone, but for the whole world.
MultiMap - a mapping site with some neat features.
MapQuest - a mapping site with lat/long coords, directions, and mapping capabilities.
JeEep.com - translate coordinates (WGS-84, NAD-83, and NAD-27) to and from Latitude/Longitude and UTM.
GeoCalc - GeoCalc is a Windows application that allows simple conversion of coordinates to various formats.