Economic anthropologist David Graeber recently published Debt: The First 5000 Years. It gives a good historical background for the MMT theory of money as debt. BTW, the book is a fantastic deal — 544 pages in hardback for only $20 at Amazon (link above).
Daily Kos, debt, history, and magical thinking
C-Span, Debt: The First 5000 Years (1 hour interview)
(h/t RSJ of windyanabasis)
I previously posted this link to an interview of Graeber by Philip Plinkington at Naked Capitalism. He also participates in the comments.
UPDATE: Anonymous reminds in the comments that David Graeber and Robert Murphy recently tangled at Mises.org
The action is in the comments