Well, bluetooth is for the most part an open standard, so any bluetooth would work with your iphone. Bluetooth is just a wireless communication standard though, what exactly do you want to do? I have a motorola GPS that does hands-free bluetooth and works pretty well. It is the TN30 model, you can find one on ebay for under $100 bucks, it also includes maps of Canada (something I needed!).
I have a BlueAnt Supertooth Light that has worked very well with my iPhone. It's a hands-free speakerphone that clips to the visor - excellent noise cancellation, voice quality, 15 hours of talk time and 800 hours standby. I've had this unit 4 years, used it in 3 vehicles and have zero complaints. You can find them on Amazon.