Bluetooth hands free car kit
 

Thinking of buying something like this.

http://accessories.us.dell.com/sna/p...nx9xw#Overview

I really wont be using the phone option too much, but would like to play audiobooks through it as well. Is it possible to use these as speakers as well?

I'm going to say no for the simple fact that if it did, I would assume they would list it as a feature.

If listening to audio is your primary goal then I would consider buying a device that allows you to playback through your car stereo. I have one for my iPhone (http://www.griffintechnology.com/products/itripauto) that I use in an older car we have that does not have a MP3 player jack and it works passably well. What kinds of phone do you have?