It's a nice idea, but has lot's of problems.  For one, it creates a central authority...what happens when that authority is compromised (perhaps shutdown by a gov't)?  I once thought about having an option on the exchanges to place a special bid that represented the amount of dollars (or other currency) you'd be willing to spend if the price went low enough...across all exchanges, the sum total of these special bids would be divided by all bitcoins ever mined to create a floor price...all these bids would execute if the price ever reached that floor.  However, people could just cancel those bids if the price started going low enough...so in the end, such a thing would be pretty useless (and needlessly tie up peoples' money at an exchange).

Maybe better indicators would help people estimate the fundamental and speculative demand.  That in turn might give some people more confidence that there actually are real support levels for the price of a bitcoin.  I'm not sure exactly what kind of indicators would help however.