Gevlon, the writer of http://greedygoblin.blogspot.com/ is inviting anyone in need of gold to apply for tips. What you need to do is go over to this post and follow from there on the how.
On the other hand, here is my list of things to stock for 3.2 that would be out in a month or so:
Titanium Ore - will be prospected by JC's for epic gems
Arcane Dust - Fly Mounts at 60 => less creatures killed => less greens looted => less of them on AH
Planar Essence- Fly Mounts at 60 => less creatures killed => less greens looted => less of them on AH
Prismatic Shards - Faster leveling => less blues D/E => less of them on AH
Arctic Furs - needed for quite a few LW (and not limited to) recipes
All types of flowers that can be mined / gathered from Outlands
I would not advise investing in Runed Orbs, but if you can get your hands on the new Crusader Orb you can make quite a few cash in the first few days (max a week).
Also Icy Dragonscales and Nerubian Chitrins are now usually under the vendor prices at AH . Get as many of them as you can, and in 3.2 they will sell for 4 - 500% percent more.
As i can see it, gold can be made in the first week after the patch hits live. And i am still sad that i've sold all my Titanium ore when it was like 25g a stack and now on my server it sells with 200 -> 300g a stack. Now time to restock.