Recently I finished a book by Frank Viola that just came out called Reimagining Church. It was his follow up book to Pagan Christianity, which caused quite a stir in some circles. I'm glad that the author followed up with this new book. It's much more hope-filled than Pagan. As Frank admits, Pagan Christianity is incomplete without Reimagining Church. (Check out Frank's blog and the website).
Viola has some good thoughts and discusses how we can understand and live out first-century Christianity as the Body in much simple forms. It's well researched and lays a good biblical foundation for organic forms of church. This was good timing for us as we develop house churches at Renew. He challenges your thoughts in several places (and probably over-emphasizes some things at a few places) but you can tell he is passionate about rethinking church and articulating the potential of making the invisible kingdom visible through the ekklesia.
I don't agree with every single thing he wrote in the book, but it still is worth picking up and reading.
It will challenge your understanding of church and help you think through what it means to be a biblically functioning faith community.