The Garmin Nuvi 500 came in last Thursday, so I got to try it out over the weekend in my SUV (we have had subfreezing highs here for several days in a row - and that's not riding weather for me). The unit comes with a quality windshield suction mount and a 12 volt auto power cord. I also bought a one of those weighted "slide-proof" mounts for the dash, as I am not crazy about suction winshield mounts. and an extra auto cord (didn't know one was included), which may get "hard-wired" onto the bike later.
Also purchased a RAM handlebar mount specifically for the Nuvi 500 (all aluminum and SS for only $41.32). The mount works great on the MC. I am going to try the unit without a DC power cord on the bike, as everything I have read says the battery has about 8 hours of useful life per charge and I NEVER ride 8 hours in one day (maybe someday if I do something criminal or its some global calamity, but otherwise NEVER).
The unit has speech directions, but its such a small unit the female voice sounds a little machine-like (the one in our Caddy sounds like a live Playboy Bunny). It couldn't find my home address, but did find my office, my church, and the local Sonic Drive In. The display is color and you can get an overhead or diagonal (they call it 3D) view. The instructions provided were a pitiful 4 pages and I am still trying to find out how to get it to do certain things.
The map display also shows your current GPS speed and the time to your destination (I thought it was current time for a couple of days and wondered why it was fast).
I know its supposed to be a handheld for walking, bicycling, boating or driving (it has seperate USGS contour maps and seperate US lakes and waterway maps also), but I would have like a screen about twice as large.
I'll give everyone another update in a month or so.