In the Nether you can get Glowstone- You can also get Netherrack, Netherbrick and Quartz Ore assuming we're playing on 1.6.
When you mine Quartz ore you get Nether Quartz - Which can be made into different type of blocks There are Quartz Blocks, Slabs Stairs and Pillars.
Theres also a lot of mobs like Zombie Pigmen which spawn in groups and they are "neutral" unless you attack one they will all swarm you D: There's Ghasts which are big floating things that shoot an explosive at you which will damage you and the surrounding blocks, but for whatever reason they can't break cobblestone. They normally stay out of swords reach but 1 shot from a bow normally takes them down. There are also Magma Cubes which are basically a Nether equivalent to Slimes, they drop Magma Cream which can be used when brewing potions.
Nether Fortresses are another thing that spawns and this is where you can get a surplus of netherbrick, netherfence and netherbrick stairs. Fortresses look like this
But most are usually half buried into the ground. In 1.6 chests spawn inside these and you can get Diamonds, Nametags, Horse Armour and more.
Within these fortresses there are rooms which have soul sand on the floor with Netherwart growing on top. Sould Sand spawns naturally around the entire Nether but NEtherwart only spawns in Fortresses. Netherwart is used for potions and can only grown on Soul Sand.
2 more things!
Blazes are another mob and they are the most annoying things in the nether, for me anyway. They float around and shoot fireballs from a distance but they normally stay low enough for you to hit them with a sword. They spawn Via Mob Spawner in Nether Fortresses and when killed drop Blaze Rods.
Blaze Rods are a necessity if you want to start brewing as you need one to make a brewing stand
Last Mob is the Wither Skeleton. I can't be arsed to type anymore so here is the wiki page Tommy, lol. http://minecraft.gamepedia.com/Wither_Skeleton
Sorry for long post