Most current DRM revolves around the idea that each person should be required to pay for their right to view/use some protected media. The rights may be temporary or permanant, and may or may not be transferrable. Ideally, a DRM system should be able to restrict who, what, when, and how.
Kelsey and Schneier propose "The Street Performer Protocol" that adds a twist onto DRM. Instead of protecting content from the public, it pays the distributor if the content is released to the public domain.
Essentially, people put donations in an escrow, and then when the content is released to public domain, the distributor (or artist) is paid.
I haven't read the paper yet, but this looks like a promising way to help free software developers pay for overhead costs.