Equally useful in your car or boat, the GPSMAP 378 has street-level maps of the U.S., as well as high-res nautical charts of 3,200 lakes and low-res versions of thousands more. $1,285; garmin.com
This downloadable application turns your cellphone into a real nav system using its built-in GPS. Get detailed directions, automatic rerouting, even a pedestrian mode for foot travel. $10/month; mapquest.com