Completely agreed. I don't want to have to opt out of a full month just because the charity featured on day 27 is objectionable. I'd much rather be able to say "send my dollar for thus-and-such charity to thus-and-such other charity instead."

A useful feature might be the ability to opt out by category or keyword. Maybe I'm not interested in animal charities, or maybe abortion is against my religion, or maybe I don't trust any charity with the word "global" in its name for some petty reason. Whatever it is, I need to be able to opt in to funding the 29 charities I'm cool with and opt out of the one I don't like.