Okay, I don't know if this really qualifies as a marriage ministry, but Shaunti Feldhahn is amazing! Her book "For Women Only" is a MUST read (you can read my review here). She also has a book for couples that I haven't read yet (there are only so many hours in the day you know!). Besides writing amazing books (9 plus 2 fiction novels), Shaunti is also a Christian speaker. You can read her short bio and start exploring her website here.