Stephen Von Worley from datapointed.net has published some beautiful visualizations of the GeoNames database. Each of the 7.5-million geographic features is represented by a single dot, colored additively: blue for water, green for land, and red for manmade structures.
Also interesting to note, besides their pure beauty, are some artifacts (for instance a band in Ireland with lower feature density) clearly visible on the visualizations. Some of them (like the US-Canadian border) are caused by different data providers (usgs vs geobase) and therefore different feature density or feature type assignment. Others are caused by the data entry process itself. A lot of GeoNames data is coming from paper maps and you can see in some areas the form of the original maps used as data source.