i use map my ride. i like it because i can save the routes and go back to look at them later. i can see distance, speed, pace, elevation and calories. i can choose to make the route public, friends only, or private. i can look at other users routes in my area to see if there are any trails i didn't know about.
i also use google latitude, like someone else said, so the wife can see where i'm at in some-what real time. just in case i bust my arse.
there really ought to be a sticky on this. it seems like there are 150 threads on this same exact topic.