I think everyone and their mother has done a version of Wayfaring Stranger, but Doc Watson was so fantastic that of course I think his is amazing. :-)
http://www.youtube.com/watch?v=k20bNYzQXs4His Sittin' On Top of the World is also pretty great. It's my go-to feel good song:
http://www.youtube.com/watch?v=Y1q4Eb34mwM
"Do you know how a man makes his way here? By brilliance of genius or the cunning use of corruption.
You must cut a path through this mess of men like a cannon-ball, or creep among them like a pestilence."
Balzac