For what you are accepting coins? Like what I can buy with them?
Therefore, I'm happy to announce that the forum is now accepting grin payments automatically, probably the first site other than exchanges to do so. You'll find a link at the bottom of the evil-fee and copper-membership pages.
I'm not so sure about Donator ranks, but i really doubt you'll be able to buy those with Grin yet. (As 10BTC would equal 10% of Grin's daily volume
)