You can see a breakdown of the number of features by country at: www.geonames.org/statistics/. In addition to being able to download the data in bulk, GeoNames also has collaboration and editing features similar to other open mapping ecosystems.
Example: Populated Places Around Mt. Everest
Before downloading, open the Readme: http://download.geonames.org/export/dump/readme.txt to make sure you are grabbing the correct files. It will also describe the column names and send you to a few other webpages for reference information. For example, you will also want to read through the feature codes at: http://www.geonames.org/export/codes.html
|Populated places (PPL) from GeoNames. Click to enlarge.|
Other data sources: USGS (DEM) and Natural Earth (Roads, Rivers,etc.).
Lastly, you can even view Wikipedia entries on an interactive map:
|Markers pop-up for entries in Wikipedia|