I've also had very good luck with my Targus
Universal Auto/Air Adapter , which has several tips to fit many different types of laptops. DeLorme Earthmate GPS with Street Atlas ($70-$160) can interface with your laptop to help put you right where you want to be. The Earthmate uses a blend of U.S. Geological Survey topographic maps, updated street maps and aerial imagery to let you navigate in real time on 2-D and 3-D maps. The Earthmate also profiles steep climbs in advance to help you avoid certain treacherous roads. TomTom has some of the most popular satellite navigation products, and although they are bit more expensive ($400-$500), they have some remarkable features. For example, the TomTom GO 910 speaks 36 languages in more than 50 different voices and can even announce street and place names. It has a 20 gigabyte built-in MP3 player and doubles as a hands-free car phone kit using Bluetooth technology. TomTom also has motorcycle and PDA navigation units, in addition to the car units.