From the beginning of creation to the present, the indisputably greatest banjo player was the great Earl Scruggs. From Earls prime to today the indisputably greatest is Bela Fleck.
The banjo, of course, is a staple of American bluegrass and folk music, but it probably has its roots in West Africa. Bela Fleck recently traveled to Africa to explore those roots recording an album and a documentary film with the musicians he encountered along the way.
You might want to check out the trailer for the film, Throw Down Your Heart , but I would recommend this short BBC audio slideshow , where you can also hear an all too short excerpt of Bela jamming in Jinja, Uganda with The Jatta Family singing Halleluiah, Its a Good Day, Jesus is the Only Answer.