Version 3.1.1 includes textures for Nether Ores and Biomes o' Plenty's Overgrown Netherrack, among others.
Some of the more noteworthy block texture changes
A sample of the moody Nether
Some item textures
v3.1.8 using multiple mods that add ores to the Nether
Various Nether ores from Metallurgy 4, Nether Ores, and others, augmented by Better Foliage