Just a forewarning, this is a Horde-only tip, though there may be something similar for the Alliance.
So quite a few blogs have talked about the wonders of flipping vendor recipes. People are either lazy, or don't know better, and will often buy recipes worth a few silver for a fair bit of gold. This is an excellent way to add some passive income, though it's something I don't often do. For much the same reason people will buy them from the AH, I don't bother getting them from the vendors to flip on the AH: a lot of them are just too out of the way. Except for one.
There are three AHs in Orgrimmar: Valley of Strength, Valley of Honor, and Valley of Wisdom. The Valley of Strength AH is awful, because that's where everyone else is and unless you have a good computer, you're going to lag quite a bit. As far as placement of other necessities (Inn, Vendor / Forge, Bank) is concerned, Valley of Wisdom is the best. But I prefer Valley of Honor because it's close to the JC daily, and now for this little gold-making gem.
Right outside the AH is a Fishing Supplies Vendor by the name of Shankys. Shankys sells three Cooking recipes: Recipe: Mithril Head Trout, Recipe: Rainbow Fin Albacore, and Recipe: Rockscale Cod. All you have to do is step away from the AH for a few seconds, grab one of each, post for whatever you'd like (I usually post in the 15-25g range), and just wait for them to sell. I can usually sell one of each a day, and while 75g isn't much, considering how easy it is to do this, there's really no reason not too. And 75g a day is excellent if you're just starting out, so keep this in mind if you ever play on a new server or make the right decision and roll Horde :)