Got bluetooth?
Thought about getting one of these?
http://www.blueant.com.au/supertooth2.htm
This is from the Australian site, not sure if they sell it in the States (if you're located there) but installation is painless, and if you remove it you're not left with holes and stuff anywhere.
Works quite well for me. I've had it for 4 months now and I still haven't recharged it yet, still has plenty of juice in it.