Global Rural-Urban Mapping Project (GRUMP), v1

Clicking on the map widget to the right will launch an interactive map tool which will allow you to zoom, pan and switch layers.

Here's an example on how to create a WMS layer instance using the Open Source JavaScript library OpenLayers.

var wms = new OpenLayers.Layer.WMS(
"Population Density",
"https://sedac.ciesin.columbia.edu/geoserver/wms",
{layers: 'gpw-v3:gpw-v3-population-density_2000'}
);