As other comments in this thread have pointed out, Unitarianism is one such project. For a very different perspective read what some neoreactionary bloggers have written about repurposing Christianity as a founding myth to fuel a form of traditionalism compatible with a high-tech society. In this society you wouldn't necessarily have to believe in the myth to follow the rites and take part in the festivals, the benefit being the creation of a sort of a lowest common denominator of cultural unity (compare to Shinto in Japan). Unfortunately, I don't know of any master-post overview of their writing on the matter and I am not equipped to summarize it better than I already have.

For general design considerations for a "post-rationalist, post-nihilist" religion, however, I recommend http://www.moreright.net/postrat-religion/. I think you will find some insight in it regardless of what your politics are. I especially like the idea of a "Truth-Myth barrier".