I'm finally revealing some of my methods for getting extremely rich on WoW. I have kept this technique a secret for a LONG time, but I'm finally ready to reveal it. I used it to make hundreds of gold when I was still in my 20s. It's one of the fastest methods of making money on Alliance side that I have found, and it used to be my biggest source of income.
There is a rare species of fish called Deviates that can only be found in the oases of the Barrens on the horde side. When eaten raw, they will cause you to shrink to a tiny size, or get "Party Fever" which is a disease causing you to randomly throw your hands up in the air and cheer (This is actually extremely annoying as it breaks all casting). This isn't so great in itself but the beauty of Deviates is that they can be cooked into Savory Deviate Delight. When you eat this, you will transform into a human Ninja or Pirate for an hour. It's not only a lot of fun, but it completely disguises your class and gear, giving you a big advantage in battlegrounds. Last I checked Savory Deviate Delight was still selling for a stable 1g per fish (It's been this valuable for years).
Getting these fish is reasonably easy considering the rewards. You will probably want to be at least level 15-20. You will need at least 10 fishing skill and you will probably want to bring a whole stack or two of bobbers. First head to Booty Bay in Stranglethorn Vale. If you can't handle the lv 45ish mobs, either do a naked death run or get an escort or summon. You're safe once you get to Booty Bay. Make sure to get the flight paths along the way. Take the boat to Ratchet and grab the flight path there. You will now be in lv 15-20ish horde territory. Head West. There are 3 major oases in the Barrens. Any of these may have schools of deviate fish. If your cast lands in a school, you will catch deviates almost all the time. Without a school, maybe 1 in 5 to 1 in 10 fish you catch will be deviates. Remember, while fishing, you're always vulnerable to horde attacks. You can avoid this problem by going into the Wailing Caverns instance. If you go in and make it past the first few elite raptors at the entrance, you can stand in the underground river and fish for hours without being bothered by anyone or anything. Fish up as many as you like. Just be warned not to snack on them while you fish. If you catch Party Fever, you will cheer and drop your pole randomly. It's almost impossible to fish like that.
Once you have the fish, you can sell them raw on auction house for a decent price. You won't make nearly as much as you could selling the cooked version, though. If you want to cook Savory Deviate Delight, you will need the rare recipe. This tends to go on auction house for about 150g. I had a friend who had the recipe and he cooked my fish for me until I could afford my own recipe. I'd recommend fishing a couple stacks of raw ones, and offering to pay someone with the recipe a couple gold tip to cook them all up for you. If you can find this recipe and afford it, I highly recommend grabbing it. It pops up on the Booty Bay auction house from time to time. It's a rare drop on horde side, so it's far rarer on alliance side. You will need over 85 cooking to use this recipe too. Once you have the recipe and skill, you can make pure profit from selling deviate delight.
Just remember, don't undercut sales on Auction house by much. If prices are down, wait until the next day. Once there was a huge influx of deviates on the market and the whole deviate market crashed because everyone undercut everyone else. It was months before everyone gave up on it since the fish became worthless. A friend and I actually got all our alts together to artificially inflate the market to get it back to where they were valuable again.