Check these guys out.
Merle Travis was a certified country legend, and did a lot of his picking using only one finger and his thumb
http://www.youtube.com/watch?v=WwYSHuOEia8
Merle was a major influence on the late Chet Atkins, who some of us were lucky enough to see do this Don McLean song live about 15 years ago in Waterville Valley:
http://www.youtube.com/watch?v=wsePsTEgiqU
And here's Hawaiian slack key legend Led Kaapana, who we saw at the Lowell Folk Fest in 2000. As Led says, "watch the fingers". This is one of his signature tunes.
http://www.youtube.com/watch?v=A8eNBdS-V0M&feature=related