Guide: How to Make Gold #9 - When you hit 80, quest hard and do dailies.

Once you hit the cap-level (which is level 80 right now), quests will no longer provide you experience points. Instead you will start earning some more gold (about 4 extra gold coins per quest). So, instead of stopping doing quests because you don’t need XP, do them for gold instead. Along with the regular quests you can also start doing daily quests. If you have your professions maxed (both main and secondary) you can do quests related to them too (like fishing, for example). This will provide you with a way to make some extra gold even when there are no more regular (leveling) quests to do.