You can now donate Bitcoins to the Darcs project via CoinCard.  There's no fee for this service.  This method of donations will be listed on the Darcs donation page soonish.

Background: Darcs is a version control tool based on a unique cherry-pick workflow.  I'm part of the Darcs core team.  The Software Freedom Conservancy manages Darcs finances but won't accept Bitcoin donations directly (because the EFF stopped accepting Bitcoin).  After processing $100 in donations manually, I figured it was easier to just teach CoinCard to handle them.