Expanded Oriental Adventures for me, too.
I would also gladly buy an Adventure Path book from Paizo that isn't a reprint of material from Dungeon. I know that other companies do such things, but I'm only in the market for a campaign book that I'm reasonably certain I'm going to like and going to use as a campaign, and for that I need name recognition. Sorry, guys.
Adventure modules by Bruce Cordell.
And, as far as books are concerned, that's about it. I have more than enough game books to last me all the days of my gaming career, especially since I make up most of my own material. I'm also not particularly interested in seeing a revival of any of the classic settings (I'll not bitch and moan if they make them, but I'll not buy them - except perhaps Spelljammer).
There is one other thing I would gladly spend a fair chunk of money on, and that's the ultimate DM's Aide for the PC. Unfortunately, I suspect that the list of requirements that I have for such a tool would make actually developing it impossible, or certainly impractical, and many of the key ones are non-negotiable.
Edit: I thought of one more. I would very much like to see a new version of Star Wars d20. As with the DM's Aide tool just mentioned, it would need to be re-written to my personal specifications, which I don't see happening. But, since we're talking about things we'd gladly buy, there it is.