Prison music and other work songs, some of the real roots of blues recorded and sounding probably very similar to the old work songs of slaves in the feilds which developed into the blues as we know it. Anyone else listen to this stuff?

Most of it is recorded by Alan Lomax, here's a couple of songs



an early recording of bukka white here http://www.youtube.com/watch?v=k_eMQ0_VgCU&feature=related

I think these, particularly the work songs are some of the most powerful peices of music ever tbh. Anyone else have any good albums of this stuff to recommend or songs they like similar?
A lot of Leadbelly's music is deeply rooted in the style, due to his own stays in prison... There's also a version of the original "Black Betty" on youtube that's amazing.
Gotta finish my work, then play some grooves, so I can turn my room into a house of blues...