So, "taking advantage" is putting it a little harshly, but we all know where gold comes from. People don't want to do things themselves, and would rather purchase ready-made goods. Let's take a quick glance at how we can capitalize on this.
There are now 5 flasks:
Flask of Flowing Water - Healers (Although they'll most likely go for the Flask of Draconic Mind)
Flask of Steelskin - Tanks
Flask of Titanic Strength - Plate DPS
Flask of the Winds - Other DPS
Flask of the Draconic Mind - Caster DPS
Each of these has a fairly tall materials list, at a total of 24 Cataclysm herbs and 6 Volatile Lifes (Lives?) but I guarantee that you can sell these flasks by the truckload on Tuesday night. Don't forget to get your friendly neighborhood Flask Master to make them, chances are you'll get a proc, and any proc is 100% profit.
Another great way to make some gold is through cooking recipes. Being a secondary skill, it doesn't get as much attention as some others, but it can be just as profitable (although slightly less now that Blizzard did away with a Cataclysm equivalent of Northern Spices).
Each recipe requires only one ingredient, which is good for us, the seller, and also good for the buyer: ever wonder why Wal-Mart is so huge? They offer a big variety of inexpensive goods. How can they sell their goods for cheap? They get them cheap.
At any rate, here is the link to WoWhead's Cooking database - you're going to want anything that gives 90 stam as well as 90 of a PRIMARY stat. 90 stam/90 crit may not sell as well as 90 stam/90 agility, for example. It never hurts to diversify, but put more money into the recipes you KNOW people want, rather than just that huntard (if you'll excuse the rhetoric) who's not really sure how to play his/her class. Remember the rules of thumb when dealing with stats - Strength is for Warrior, DK and Paladin dps, Agility is for Hunters, Enhancement Shamans, and Rogues, and Intellect is for magic DPS and healers (most of the time).
-Flasks and cooked food can net you a tidy sum
-Be sure to know the market, but also to diversify to cover all the bases (or as many as you can)