A handful of classes within the game open them selves up well to putting together a service based gold making system
For instance, healers are usually generally desired in to groups.
Quite a few gamers want to be able to run instances, yet they don't have the time to wait for a group using the random dungeon timer. Now, for these types of classes which are really in demand (healers, tanks mainly), this gives them a great chance to gain access to groups, with barely any waiting. Less waiting around... will mean much more money in Wow! I believe tanks have the easiest time, especially getting into dungeon instance groups. Healers tend to have to wait a couple of minutes, but it is a far cry from what the DPS has to put up with.
It's actually not really easy now. You see, before you would just drop your main group just after your queue which left that group awaiting a certain class. It's not so simple now regrettably, because you have to keep in the group. Leaving behind this group currently definitely will result in kicking any person you queued with out from the dungeon too. So you will must have to remain to earn your gold. As long as you possess the skill and gear to take care of the dungeon, this could not be too bad of a problem. Having a very good group build will probably help to make most of these instances much simpler obviously.
I am hoping right now you are seeing there are more methods to make gold within Wow.
Another tip is that Mages can make portals in these instance areas. Depending on the time of day, and the need of the folks needing a port, it is possible to earn hundreds of gold an hour by selling portals. At its peak, it wasn't uncommon to be given up to a 100 gold to get a port out of Dalaran. In all honesty, it was getting quite challenging to get groups sometimes because everyone was checking out the new areas, the good news is, I think people are returning to Azeroth, so this should make instances running for gold farming a good option once again. The neat thing about this is that it allows you to work other methods, for example manipulating the ah, at the same time.
Essentially, all I am saying is, just about every class (though Tanks and Healers have an easier life!) has its own ways to generate money in Wow. Even if you don't use them as a major form of income, they're a great way to make extra gold.
The end of the day, it's all about having fun making Wow gold together with realizing that each and every class will typically have something 'special' to help he or she generate lots of gold in World of Warcraft. You REALLY do not have to mine or fish for a lot of time by your self to make money. To me, it is so boring! Lol