In yesterdays New York Times, there is an article about a couple of businesses that are basically pawn brokers for Art World.
They basically name names while at the same time saying they are confidential. One of the biggest names to use one of these brokers is Annie Leibovitz, who borrowed over $15 million dollars, and gave up her negatives and "future work" as collateral. You are in deep when you have to give up "future work".
It's worth a read. See it here.