Let's say we have a formula like this:

The top marginal rate is calculated as the (UR * 4)+10.

At 9.8% unemployment, the top tax rate would be 49.2%.
At 5%, the rate drops to 30%.

I see many advantages to this:

1) Government receives more revenue to stimulate the economy and subsidize unemployment insurance when the economy needs stimulating, less revenue when it doesn't need stimulus.
2) The pain of economic downturns is shared across income brackets.
3) The wealthy are more likely to invest in domestic job-producing industries instead of off-shorers and unproductive things like derivatives, shifting the economy toward domestic production rather than speculation.
4) The rich get to control their own tax rate through their investment decisions. They also see their investments grow as the well-employed consumer base grows.

I've been musing about this for a while and was surprised when a libertarian co-worker said he liked the idea. I say if the rich really do create jobs like many claim, let them prove it, and let them have some skin in the game.

So what do you think about the idea generally? Has this been proposed before or even attempted somewhere?