Natural Earth is a public domain map dataset available at 1:10m, 1:50m, and 1:110m scales. “Featuring tightly integrated vector and raster data, with Natural Earth you can make a variety of visually pleasing, well-crafted maps with cartography or GIS software.”

Natural Earth Vector comes in ESRI shapefile format, Natural Earth Raster comes in TIFF format with a TFW world file, all Natural Earth data use the Geographic projection, WGS84 datum.

Unfortunately, only zip-File Download and no OGC Web Feature or Web Raster service is provided.