Mav and I had a chat today on IRC about the arbitration committee, and we came to a somewhat different and more aggressive model to the one Michael Snow is proposing.
I can take very little credit for this, since our discussion basically consisted of me putting forward my ideas, Mav saying his were better, and me agreeing.
The basic problem, as I think we all understand, is that the Arbitration Committee is slow. It is slow because some of the members don't reply to emails and don't watch the relevant pages on the wiki. What emails they do send are few and far between.
The first and most important measure to improve the speed of the AC is to reduce the necessary quorum to three members. Decisions are made by a simple majority. Any member of the arbitration committee may request a review of such decisions by the full committee.
The second is that deliberation should be conducted by IRC, not email. Cases will still be accepted on the wiki, and findings will still be announced on the wiki. But deliberations will be performed by any and all AC members present in #arbcom.wikipedia, as long as there is more than three of them.
Under this proposal, the size of the arbitration committee can expand to meet the ever-increasing demands placed on them. Preliminary judgements leading to blocking pending a full review should be possible within minutes of a request.
I'll put up this proposal on the wiki some time in the next couple of days, unless someone else beats me to it.
-- Tim Starling