The New York Blood Center continues to appeal for plasma donors via a form on this page, "Convalescent Plasma COVID-19 Donor Request Form":
https://www.nybloodcenter.org/donate-blood/convalescent-plas...
https://www.nybloodcenter.org/donate-blood/convalescent-plas...
Mt Sinai's study also accepts people that did not get tested for covid-19 at the time of infection. They will accept plasma and then test it for antibodies, which has the handy side effect of telling you if you already had covid-19. I'm scheduled to donate there next week.