Morrowgrain
This is not necessarily a way to make money but more a way to save money (although you can make some gold off it and I will explain that a little later on).
To start off you need to be at the Morrowgrain research portion of the quest chain lines Assisting Arch Druid Staghelm for Alliance and Assisting Arch Druid Runetotem for Horde.
If your 80 you probably already started this chain and may be at the appropriate quest already.
Once you get to this part, you can start to cultivate 1 Packet of Tharlendris Seeds, and 2 Un’Goro Soil. You then receive Evergreen Herb Casing. This will give you a random herb or 1-5 Morrowgrain. Once you get 10 Morrowgrain you can turn it in for the same rep as 20 Runecloth ( 75) for Thunder Bluff or Darnassus.
The reason why I chose to level my rep this way, is due to the increased price in the herbs that come out of the cultivation. I sell the herbs for as much (sometimes more) as what it cost to buy the Un’goro soil off the auction house.
The biggest downside is it has a 10 minute cool down with the cultivation. In order to get them done, I would just try and do some in between pulls in raid, or questing. This method will take a while, but will cost you less (overall) than Runecloth.
Now that I am exalted, I still have Un’goro soil on my snatch list for up too 25s each. Most herbs that come out of it tend to be worth 1g+ and Morrowgrain sells on the AH for 2g+.
This isn’t a high profit method, but something to do in your down time once in a while when you can get the soil for cheap.