I found a cheap way to add Bluetooth audio (A2DP) streaming to my car -via the aux port. The audio quality with Pandora or SlackerRadio is great. You can't beat the price if you want a cheap way to add bluetooth to a car.
http://dx.com/p/bluetooth-2-0-a2dp-a...ck-8422?item=1
The mic also works if you want to use this with a phone, but the quality is average at best.
Note: The only bad thing about this so far is that you have to charge it every few days. Also, shipping takes about 2 weeks since the above website where I found this ships from HK. You may be able to find this on Amazon, but I took a chance because it was cheap (under $20) and happy with it so far.