If you own a level 80 mage or paladin in WoW you are in luck. The mage and paladin is considered one of the best classes to farm northrend gold with. This is because of thier ability to lure multiple mobs and kill them at the same time. If used smartly in combination with certain professions, this ability can be one of the best for making northrend gold. However, like everything in life, having the ability to do something doesn't mean it will be easy. Lets analyze thier abilities that can be used to farm gold.
The utility of the northrend wotlk mage or paladin is the ability to perform many Area of Effect spells. These are spells that affect multiple mobs at the same time, rather than one at a time. This gives them the ability to destroy multiple monsters at the same time, thus increasing the amount of mobs killed per hour.
The mage's AoE abilities include frost nova, blizzard, flame strike, arcane blast, cone of cold, and a few others. These spells typically cost more mana than single target spells but they put out a lot of damage to multiple mobs, this allows you to kill 6 mobs for the same amount of mana and less as it would take to kill 3.
And the paladin has the spell consecrate. Although at first glance this spell doesn't look very useful, if combined with the paladins high armor and ability to heal for low mana it can become a deadly force for all mobs. By luring 3 or so mobs and consecrating while pulling to other mobs, you can literally fight for an hour or so without ever taking a break.
One thing you can use these amazing abilities to farm are the multiple primal essences in existence. Research which sells the best on your server and then find a spot and go to work.
Another good way to make some serious gold is to take the skinning profession and find a spot that is filled with beasts. Using AoE with skinning can be a VERY VERY profitable use of the skill.
There are many ways to take advantage of the mage and the pallies abilities in the World of Warcraft, however to find good areas or better ideas to combine with these abilities I suggest you look into a northrend gold guide. These guides are packed with relevant information for those who want to change their financial future.