One of my favorite methods of making gold is reselling vendor items. This post isn't about what vendor items you should sell, you probably have heard of all of these. It's of a brand new way of acquiring these patterns in Cataclysm that most people haven't yet realized.
Captain Samir has many patterns in his inventory that were once "Limited Supply" items pre-Cata. He is found in Kelp'thar Forest, and is really easy to get to if you have done a bit of questing in Vashj'ir. He has patterns that some completionists may be hunting for but the big scores are Plans: Adamantite Rod and Plans: Eternium Rod. These are the only two blacksmithing rods that blacksmiths can't make without the plans, and they were previously bought in limited supply. Now you can stock up and fill your bank with these for future postings! I suggest posting 1-2 at a time, so people don't go googling them!
These patterns are great because both rods are required by enchanters, and when leveling enchanters spam trade looking for a rod and a BS realizes he doesn't have the recipe, the first thing he'll do is check the AH. Price appropriately and you'll have a nice flow of income from these things. As an added bonus you can craft them on your BS and mark up the prices because they're hard to come by!