11 hidden/unused terrain textures I found while digging throught the files.
Most of them are rehashed versions of already known textures, but some (Meinhoff Grating or Port Zion Tiles) seem to be unique.
The attached SC2Map file has all the textures arranged into two tilesets. Simply ctrl+c/ctrl+v them into your maps/mods.
Big thanks to the person who made the list at http://starcraftmapping.de/wiki/Tilesets (helped a lot with finding the rest of the textures)
Meinhoff Concrete
Meinhoff Craters
Meinhoff Grating
Meinhoff Panels
Meinhoff Rough Sand
Meinhoff Sand Dunes
Meinhoff White Sand
Aiur Grunge
Port Zion Tiles
Tyrador Big Bricks
Tyrador Bricks