I need an expresscard 34 to firewire 800 adapter for my macbookpro.

I had to send back one adapter from newegg. It was specifically advertised as compatable with mac. It wasn't.

I'm looking for recomendations on an adapter that does work with mac.

Keep in mind, this will NOT work with aluminum body MBP only previous generation.
Sonnet 2 Port FireWire 800 ExpressCard - FW800-E34 - Buy.com (http://www.buy.com/prod/sonnet-2-port-firewire-800-expresscard-2-x-9-pin-ieee-1394b-firewire/q/loc/101/205985242.html)
Since you have the 17 inch, I have no way of knowing which version you have.

Word of advice, in the hackintosh community they tell you to find out which chip the card uses, the majority use Texas Instruments. These are the problem for non-G5 computers. You are looking for an Agere FW643 chip, as these are native on the Mac Pro.
Good luck.
-C

I have the latest, bought in June, MBP 17".

Are there no card adapters that will work for me?

Way to go apple.

Sonnet makes 2 types of FW to EC34 cards; the model from New Egg is not compatible however the "Pro" model is.

Here you go:

Sonnet - FireWire 800 Pro ExpressCard/34: Faster FireWire Connections (http://sonnettech.com/product/fw800expresscard34.html)