I've been working on an extension of the idea behind the PGP web of trust model for some time, we need to allow user control of anonymity while allowing for reputation and differing levels of identity proofing. Our system of freedoms in speech and thought require that identity not be centrally controlled and monitored by any single entity, not even a trusted government, but the social contract between human beings requires that people have reputation and repercussions for unacceptable actions. In modern cities as well as modern online fora there can be severe negative behaviors because of relative anonymity and lack of repercussions. Some rating services and even some legal systems now encourage deletion of negative records, a "right to have sins forgotten". This is the opposite of the sort of social contract technologies we need to enable to change social behavior in a positive way. Immediate benefit could be seen for security researchers, exploit writers, systems crackers, white, grey, and black hats, users of online dating services, and those purporting to offer opportunities for artistic or professional careers. Benefits to society as a whole could be much greater, if it gains wide currency.
The other meaning of currency brings us around to bitcoin. Adi Shamir recently discussed what interactions absolutely require strong identity proofing for society to work, and what interactions require anonymity. The decision should not be driven by fear of bad actors, "The only thing we can't make is something we can't think about." as Charlie Sorenson so aptly put it, so we can build a system that drives bad actors out, whether they are criminals, attackers, or politicians... while not only allowing but encouraging freedom of thought, expression, and creativity. I'd like to go back to Steven Levy's definition of a hacker as a particularly gifted and creative programmer or maker, the pursuit of elegant hacks and the hacker ethic at MIT in the 50s, the goal is still no less than improving the world.