You can either upload data from a GPS unit, or draw a map on a Google map. The drawing option snaps to streets, so it makes it really easy. You also get an elevation profile for the route - I love that stuff.
However, sharing the maps isn't easy. When I cut and paste the code they give me to embed the map in my blog, the area where the map should be is white.
I'd love to show you a list of the maps I've created, but the link they give me is retarded (sorry - but seriously... it is. Go ahead. Click the link.).
You're on the right track bikely, but you could be so much better.