Well I did this about a month a gold and it's real nice. With WOTLK, the Isle of Quel'danas (Sunwell island) became a ghost town. Even though it's become a ghost town, the node respawns are still the same.
There are exactly 6 nodes throughout the island which never ever move. They all have like a 3 minute respawn time so you can just go in a big circuit mining them with occasional rich adamantite and khorium. (Click isle of quel'danas to see the nodes.) http://www.wowhead.com/?object=181556
If you have any kind of water walking you can do the entire route in like less then 10 mins and only fight 1 to 2 mobs! You'll NEVER run out!
Yeah, I know, adamantite doesn't sell like it used to, but if you need it or want to sell it for cheaper, this spot is amazing.