Nice offer from Newegg.com on this iPhone cradle, just $13 shipped (was $40). Includes a free 2-piece headset.

http://www.newegg.com/product/product.aspx?Item=N82E16875992158

Give your iPhone GPS, podcasts, and phone calls a sound boost. The built-in amplification system in the cradle doubles the volume from your iPhone speaker making it easier to hear your voice-guided directions, calls and more. It mounts on any dash with no installation required. The cradle holds your iPhone safely and securely on even the roughest terrain yet uses no adhesive or hardware so it can be repositioned for optimum GPS reception and moved easily from car to car.