As you may have read on DailyKos, there's a movement to separate marriage from civil unions. Marriage would be a strictly religious observance while civil unions would be granted by the state.
When my wife and I were married last year, we filled out two separate contracts. One was the North Carolina issued forms and entailed the legal benefits and responsibilities of our union. The other was a contract known as a "ketubbah" that is signed by husband and wife in the Jewish tradition and indicated our spiritual bond. Our wedding was performed by a rabbi, but she had to be licensed by the state to do so as well.
From our experience, it already seems to be that there are two separate institutions. Why not make it official? Churches and other houses of worship would not be forced to issue their religious marriages to anyone (e.g. a Catholic church would likely have refused to marry me and my wife), and civil unions will be available to any pair of consenting adults not already civilly united with someone else. Problem solved, marriage is saved, and everyone is treated equally under the letter of the law and our nation's constitution.
I'm considering crafting a petition to this effect, but don't know who to send it to, how to get signatures, and what other organizations to involve. I'm already a member of HRC and recently joined straight FOR equality, but don't know if there's a better place to start than with them. If you have ideas or would like to help out, please contact me. Let's make the world a better place together.