Here’s a place for me to stuff links to good tools for people who run working-groups. It’s going to be a bit ICANN biased, since that’s where I do my working group chairing. But others might find this useful as well.
IETF draft — On Consensus and Humming in the IETF [note to self: go back and periodically update this to the latest version]
Wikipedia has a good starting-point article — Consensus Decision Making
Mind mapping software
I find “live mind-mapping” to be helpful when leading certain kinds of conversations. There’s a very good mind-mapping program that’s open source called Freemind. Here’s a link to the download page (it runs on most platforms).