The Quake Revitalization/Retexturing Project published the first release of a complete set of map replacement textures for Quake. The aim of the project is to replace original textures with a new faithful ones in a higher resolution and detail. The set now replaces all the existing Quake map textures. There's also a separate pack that replaces some of the item textures.

Head on to Quake Retexturing Project (QRP) website to download this unholy package!