If you are a high level crafter, then you better be using your profession's 20-hour or 4-day cooldown as much as possible. Those of us that are big auction house players and crafters, use this tool ASAP when it is off cooldown. Here is am aiction house trick I will share with you to help line your pockets with super easy gold.
The basis for this money making works best for players that have just a few or only one crafting profession. Every day I transmute an epic gem on my alchemist, hoping to get a multi-craft proc. That gem is then either banked or mailed to my jewelcrafter, who turns it into whatever epic cut I can sell for highest, or is in highest demand for easy profit making. What if you are just an alchemist and don't have a jewelcrafter to cut it. Well, you can always tip a jeweler and sell the new cut gem on the auction house. If you are new to this, are still levelling your jewelcrafter, or have very limited materials, you could just bank it. Eventually you will run out of materials, or you will hit a point where someone is raping you on the cost of materials on the auction house. You definately want to be using every single cooldown as soon as you can to maximize profits in World of Warcraft.
We all know that once you run out of materials you can advertise that you are selling your cooldown for a fee. Here is something I learned that can be very advatageous and most people are not doing it. Sell all of the items you have pre-crafted that have a cooldown, by trading for the materials plus the fee you would charge. Most buyers need more than one of the item and will be glad to pay you a fee for each of your finished products and you often can get a bigger fee per cut since you are helping save them the time of hunting down multiple people to buy their cooldowns from. Example:
I charge a 30g fee to smelt Titansteel Bars. When someone is in trade chat looking to buy a smelting CD, I ask them how many they need. If they need 8, they trade me 8 sets of mats plus 30g per set and I give them 8 finished titansteel bars. This greatly decreases their search times and often they will continue to come back for more. Now you have 8 days worth of mats to continue smelting for titansteel bars.
Now figure in a transmutation master. Not only are you continuing to churn your product out, but they never even see any multi-procs, thus eliminating the arguement over who gets the extras when the alchemy transmutation master procs.
Obviously you would make more gold by using your own items that you craft to flip into higher profit items, but this trick works very well for limited crafters, or those who are still learning markets, or for anyone who has a surplus of items in the bank they are just sitting on. Put those titansteel bars, epic gems, and 4 day CD crafted tailor weaves to good use.