Off the top of my head I'd be potentially interested in the following (in this order):
Age of Empires III (and expansion packs)
Red Alert 3
However, by all means let me know what you have as the list of Mac games isn't exactly extensive.
Oh, and I have Command & Conquer 3 Tiberium Wars (on Mac, obviously) as a potential trade if interested.
- Crazy Jamie
Payment by BT (I don't have PayPal)