Re: I'm not a fan of selling data.. but
OPT in and Informed consent for each and every separate data use is the only way to go.
Well said. And I've just done this. So I've donated my DNA to a research group looking at possible genetic linkages to something I've got. The consent form stated they'd only sequence a limited number of genes for the purposes of their study, and no sharing outside of the study. Ok, so that could potentially mean other researchers studying the same thing, but given some enlightened self-interest, it was good enough for me to enrol.
One clause that stood out was regarding patient access to the results. Which AFAIK would be a right anyway, but largely meaningless to a non-geneticist. Then again, DNA stripes could be turned into a personalised desktop backdrop, or CTAG<etc etc> chunks used as a personalised crypto sig I guess.