There is a vendor in Moonglade named Lorelae Wintersong. She sells the recipe for Runed Arcanite Rod.
This enchanting rod is required by all enchanters to be able to progress to higher levels of enchanting. The problem is that it is ONLY sold in Moonglade. Nowhere else in the world. It is also a limited item, on a short respawn timer (meaning it may not be available when you go to Moonglade to get it). So for many enchanters, it is a bit of a pain to get.
We druids, on the other hand, have the advantage of being able to port to Moonglade whenever we please.
Remember: In WotLK, a lot of people are rich and lazy.
Many people have tonnes of gold and nothing to spend it on.
They are also lazy, and would rather pay exorbitant prices on the AH than have to go get something for themselves. This is particularly true of people who decide to reroll professions and then power level them. They don't want to travel all over the place - they want to be able to stand in Stormwind or Orgrimmar and power level their new profession as fast as possible.
If a new pattern or formula requires someone to go halfway around the world, that's a pain. If there's one up on the AH for 30g (maybe even more), they'll just snatch it. It's not worth the time and effort to travel to get it themselves. I have done this myself a number of times; I've paid 20g for a stack of meat to level cooking, or ridiculous prices for cloth and herbs... all because I don't want to have to keep flying back to town to train the next levels.
In the case of the arcanite rod - some people don't even HAVE the Moonglade flight path. I've even helped friends get the pattern - when I've overheard them complain about having to go "all the way to Moonglade", I've offered to port and grab it for them. It's a real hassle to get that pattern if you're not a druid.
As a level 10+ druid, you can take advantage of this inconvenience!
Make a quick 15-20g+, casually
I suggest any time you are about to hearth and log for the day, port to Moonglade first, grab the formula, then hearth afterwards. If you're levelling, grab it whenever you head to Moonglade for training. I grab one whenever I port there, for whatever reason.
It will cost you 2.2g (less with rep), and will probably sell from 15g upwards (personally if I was a non-druid I would likely pay up to 100g if it meant I didn't have to mess around getting to Moonglade).
For those of you at 80 with high incomes, this may not be worth your time.. but considering that this is easy for any druid of level 10 and up to do, if you have 2g to invest, you can quickly turn that into a lot more. Very handy for that first mount and training costs.. especially for crazy rerollers like myself, with no "main" feeding cash to the new druid.
And those of you who are saving 5000g for epic flying may be looking for tips on how to squeeze as much gold out of the game as you can. This tip might be worth 10g or it might be 100g, depending on your server - but regardless, with Teleport: Moonglade at your disposal, it will only take you 2 minutes of your time.
Particularly helpful for lowbies, but also for the thrifty, seasoned druid. Every little bit counts, right?