This blog post has a nice overview of how Approver.com works, so I won’t try to duplicate. I wonder if some School of Informatics student or alum might think to come up with a similar tool for the Decider Protocol (PDF) that Marty advocates in his HCI classes. (Decider.com is taken, but not DeciderProtocol.com …)
There is a lot of advantage, mainly in terms of stakeholder buy-in, to demanding consensus as part of decision making. Marty uses a stripped-down version of the full Software For Your Head core protocols by Jim and Michele McCarthy. Mostly, we found it useful for in-conversation decisions, though, and never used it for approval of deliverables. Maybe it wouldn’t work as well there.