  Internet companies derive value from users by recording and influencing their
behavior. Users can pressure companies to refrain from certain invasive and
manipulative practices by selectively withdrawing their attention, an exercise
of data leverage as formulated by Vincent et al. Ligett and Nissim's proposal
for an institution representing the interests of users, the data co-op, offers
a means of coordinating this action. We present one possible instantiation of
the data co-op, including the Platform for Untrusted Resource Evaluation
(PURE), a system for assigning labels provided by untrusted and semi-trusted
parties to Internet resources. We also describe PURESearch, a client program
that re-ranks search results according to labels provided by data co-ops and
other sources.
