I think some of the European exchanges do it. Your mileage will vary I guess.

I think some of us with smaller older rigs can do the alt,coins and trade for usd or bitcoin if the bubble bursts. I would be very careful to watch and when it goes down again buy some because if I had BOUGHT BTC instead of mining gear I would have made a killing. Live and learn.

So don't be afraid to trade for say litecoin then USD.

On another note, I have to say BTC merchants haven't marked down any of their prices in the past couple of weeks they still have stereos priced at 1 BTC Yikes.