Basecamp is the Mac sort of version of Mapsource. If you are both clever and lucky you can design routes on the Mac and export them to the Garmin and retrace them. Its easy to import routes into Basecamp from the GPS. But what about sharing them on a blog or something similar in a more intelligent way than just taking a screenshot and posting the picture? This is useful but not quite it: http://rolfje.wordpress.com/2010/06/30/how-to-share-garmin-routes-with-your-friends/
Then there’s Garmin Connect but that doesn’t seem quite right.
What about this from Motowhere. Its a route I’ve placed there a while back and it should show up here:

What about satellite images?

Here’s an import from another motorcycle route sharing website Open Road Journey. It seems a bit more developed than MotoWhere, where the ‘forums’ are moribund and just full of spam. ORJ appears to have real articles on it:

Finally, there’s Everytrail of course.It seems more sophisticated when tacking GPX files from the Garmin.
the ‘back’ way to Ipswich and a route around Cambridge at EveryTrail
EveryTrail – Find trail maps for California and beyond