Enchanting

Enchanting has many ways to be profitable.

Buying armor/weapons on the AH Disenchanting them and selling the mats for a profit are popular ways.

Running/Soloing Instances for shards is also very profitable.

And last but not least selling the enchants them selves. Getting rare enchants and an addon to shout and list prices for you are pretty much required.

*NEW* New in Patch 2.4 a recipe called void shatter has been added to the high end Enchanting skills. This will help bring the price of large prismatics down a bit and make Void crystals more usefull !