Protomaps is "an open source map of the world, deployable as a single static file on cloud storage". It involves some very clever technology, rooted in the PMTiles file format which lets you create a single static file containing vector tile data which is designed to be hosted on static hosting but can then serve vector tiles to clients using HTTP range requests. …
Inspired by Brad Neuberg I decided to take a look at the SQL features in the GDAL family of tools. …
Natural Earth (website, Wikipedia) is a a public domain map dataset. …
Via Tony Hirst I found out about MapZen's elevation tiles, which encode elevation data in PNG and other formats. …