Interesting idea. I wonder if anyone has stepped up to prevent the chilling effect of DMCA takedown notices?

It seems like a non-profit could handle this role where they act as a proxy where the victim of the notice asserts they have copyright, sends the information to the proxy and then the proxy acts on their behalf?

Interesting idea. The proxy service would most likely be in the form of a "copyright agent" service for copyright/DMCA takedowns, with some degree of privacy protection for site owners. This would enable large scale monitoring of abuse.

The "act on their behalf" might be considered legal representation. As I understand (IANAL), the EFF as an organization doesn't provide legal representation to others, and more commonly refer them to a lawyer or law school clinic for further assistance.

Righthaven got struck down because they were only assigned "right to sue" and not ownership or exclusive rights to the copyrighted work.

Isn't that basically what Righthaven was doing, on the other side of the legal courtroom? Taking control of the copyrighted work and suing infringers on behalf of content owners?

Not quite. Righthaven did not receive an assignment of the copyrights themselves, they tried to get only a bare "right to sue" that is not recognized by law. The copyright holders were none to eager to give up the entire copyright, after all, but this reluctance doomed their lawsuits.

If he were to fully assign the copyrights to the EFF, they would not run into the same trouble Righthaven did.