TrailRunner

If you live in the US you might want to check out topozone. It delivers the Web's most complete set of digital topographic maps, aerial photographs, and related mapping information to the professional and outdoor recreation communities.
The Web-Service tool combines all available USGS topographic maps in one Interface. Maps scale down to 1:25000 and have topographic altitude information drawn in.
The USGS (U.S. Geological Survey) serves the US by providing reliable scientific information to describe and understand the Earth.

TrailRunners View Menu now has a direct link to topozone. So if you select a calibrated waypoint, you can check out what map data is available at topozone. The example above depicts the Central Park in New York.
> New York Central Park at topozone