OpenBSD, while mostly free, distributes binary-only firmware and often downloads more on first boot.
LibertyBSD is pending review by the Free Software Foundation, which maintains a list of free system distributions. Other distributions on their list include Trisquel, which is based on Ubuntu, and Parabola, which is based on Arch.
To ensure the continued development of LibertyBSD, releases will not be available for download until 3 BTC has been raised. After that, future releases will be available at no cost. 10% of the money raised will be donated to the OpenBSD Foundation.
For more information, see http://www.libertybsd.net/
Contributions can be sent to 1BFQEqzhxTbvfjZ3f9eoTbeEBgJdkVcj4m