I have a Garmin Nuvi 765 that I use primarily in the car, and a Zumo 665 for my bike. But lately I've been using my Droid phone with Waze in the car and it is making me want to find a good mount, waterproofing to use on the bike. The Waze app is a "social GPS" app. You log in and their routing engine uses your speed (and other users) as part of the algorithm to calculate the best route. Living in Boston, rush hour traffic can really impact travel times and so far Waze has proven by far the best at minimizing travel times compared to the Garmins or the Google droid app. The second advantage is related - it allows you to report police. Probably wouldn't be that helpful on a back road in Northern Maine, or when the police are on the move, but for stationary speed traps in "Honey Holes" in MA and NH it's been great. You can also display GPS speed to help set your cruise control on the highway. Finally, if other friends log in you can send them your destination see where they are, or text them. The Garmin still has a number of advantages. First, you can make your own routes with as many intermediate waypoints as you want: there are lots of routing options, where waze might give two or three. Second is the display of speed limits, invaluable on back roads. Finally, the ease of use with gloves, waterproofness and secure mounting all favor the Garmin. But for commuting, check out waze - it's free.