Questing

At 70 you get Gold instead of Experience for quests.

This is one of the fastest ways to make gold but it obviously runs out after your caught up with all quests.

It helps to save up as many quests as possible when lvling from 60 - 70 by just grinding on rep mobs or running instances.

At 70 with some decent gear and a flying mount you can breeze trough most quests and can even do the 2 - 3 man ones of the lower 60s for the good rewards.

There are a few quest hubs such as Netherstorm and SMV that can net a lot of gold if you haven't done them for XP.

Ive released this guide as an article with slightly more info here