A lot of collectives use consensus to create non-hierarchical organizations.

For more background, ActUpNY.org gives a good overview.

If this sounds like something you and your group would like to implement, I highly recommend Consensus: A new handbook for grassroots social, political, and environmental groups by Peter Gelderloos. This is the model Food Not Bombs uses. The handbook includes the consensus process, meeting structure, awareness of group dynamics, and an appendix of sample dialogues.

Resolve (a non-profit organization dedicated to advancing the effective use of consensus building in public decision making) also has an online guide to consensus that is a quick and easy reference for the process.

There is also the Basic Intro to Co ops Zine (PDF) from ZineLibrary.info, covering the topic well and hey, it's a zine!