I've been trading on bitfinex since the day of the big sell off (actually discovered it that morning and moved some of the meagre amount BTC i own from mtgox to there). I find it fantastic because its a trading platform that provides rich trading options, unlike mtgox, which doesnt even have stop order functionality which i wanted to protect against the "bubble popping".

I managed to open a short position on BTC at $220 during the sell off to hedge my current BTC holdings which means i didnt have to sell my BTC on mtgox during the lag period. I still have all those BTC on mtgox.