I am using a TomTom 700.(
http://tomtom.com/ )The brand appears to be fairly new to the U.S. It is a compact portable device that can be used in Europe aswell. It's easy to use. I have my Nav mounted on the dash next to the base of the A pillar, basically on top of the sideglass defogger vent. I tried mounting it above the rearview mirror but I find that I can keep my eyes on the road better with the A pillar location. Incidentally, it can also give you traffic reports and weather via a bluetooth phone. I haven't used this feature yet - I don't have a bluetooth phone yet. My friend has a TomTom 300 and is trading up to the 700.