GPS and Navagation software exists and it's good
A little more than a year ago, i asked the same question. MANY google searches later i found just what i was looking for. The street level mapping and GPS software is about $40. It's called Route 66. I love it.
http://www.66.com
There is another software package for avation and nautical charts. You have to buy the charts from 3rd parties, but it's pretty nice and they update frequently. This, however, is of interest only to those with specialized needs. It deals with charts very well and also works with NMEA gps's (and others) much better than i expected.
http://www.gpsnavx.com
go have fun. i've been playing for a while.