Leaflet NationalMap
From charlesreid1
An example of how to hook up Leaflet to use the USGS National Maps tile set.
http://viewer.nationalmap.gov/example/maps/Leaflet_Example.html
An example of how to make a topographical map:
http://viewer.nationalmap.gov/example/maps/pqs_profile.html
The above example uses a tile set to render contours (contours are represented as images), whereas the D3 Map project I'm working on uses a shapefile containing detailed contours represented as polygons (and therefore much slower).