People think usury means to lend money at interest, or at excessive interest. But it should be understood to mean any attempt by a person or organization to place his neighbors in such a situation that they face hopeless debt bondage.
Forgot to mention - in keeping with you comments about 'debt bondage', it appears that Grameen has managed to avoid that by making repayment terms manageable. That, and the concept of making micro-loans w/o collateral, are the program's revolutionary aspects.