Druid is probably the single most versatile class in the game, even moreso than the other hybrid classes in the game. Unfortunately, that same versatility makes it a little difficult to determine the best way to do simple things. Today, we're going to talk about Druid gold farming. Druid has two good DPS specs, but we'll focus on the more solo-efficient spec, Feral. Not only does Feral have very high DPS, it has virtually no downtime unless you have a series of particularly bad pulls, thanks to the efficiency of its mana usage (for healing only).
So, here's the spec I recommend for druid gold farming: http://www.wowhead.com/?talent#0ZxGMcfrbbeR0IzAkbgczb:NcoVMz
And now that we have the spec, lets discuss damage dealing and tactics. Dealing damage is pretty straightforward:
Pounce -> Faerie Fire (Feral) -> Mangle -> Shred -> Rake -> Rip or Ferocious Bite (depending on how much health the enemy has left)
Most enemies should die after one round of this, but for the few that survive, another Mangle or two should end them. If you face too many enemies that are lasting a long time (unlikely unless you just hit level eighty), it's important to slip an early Savage Roar in there, too. Though for the most part, you won't need the extra damage of Savage Roar or any extra Mangles.
A few more tips: Pick your pulls carefully, be careful about players from other factions if on a PvP server or farming in Wintergrasp, use your flying mount to move between mobs unless they are close enough together to make the cast time a waste, use cooldowns often.
Feral is actually a pretty damn complicated melee DPS spec, but fortunately you get to avoid most of the headache involved in raiding during your druid gold farming; enemies don't last so long that you need to juggle a bunch of bleeds and buffs for maximum damage.
I hope this guide has helped you out some; if it wasn't in-depth enough or you need more gold-earning tips, then I'd suggest getting a dedicated gold guide. Check out my Gold Guide Review, where I compare various popular gold guides, and find one that sounds good.