I know how many times this has been suggested, and I can't do it as professionally as everyone else, but I want to be heard at least.
Glowstone on the ground and in abundant amounts.
They maybe could grow in this area, a new block created every once in a while, but a cap would have to be added to prevent glowstone walls
Appears like a more "solid" netherack, you can find it generally like a random ore, sticking out to the surface of the Nether, and in Nether caves.
Can be used to make netherstone tools, smelting all that it mines (If smeltable) and a smelting enchantment could be added, but based on chance, that mirrors this ability.
Small netherbrick buildings that have broken down; no door, blocks are missing, small netherwart growths, with only misset glowstone for lighting.Is set in the netherack lining the open space of the Nether.
Can be used as havens from ghasts when adventuring the Nether, and a more convenient location of netherwart. (This can help to be livened up)
I can't think of anything that would help the Nether's popularity without having to go greatly in depth, but these are my thoughts.