If you're looking for an HDMI to mini display port adapter for the MacBook, whatever you do, don't buy one at the Apple Store! You'll pay 10X what you need to. Amazon.ca has several adapters that get lots of good reviews (better than the ones the Apple Store sells for >$30) for under $5. Best Buy is even worse - we were looking at them this evening and they were $40 there!
Clearly, some companies think we Mac users have more money than sense.