I've had success on Bter, Cryptsy, Vircurex, and BTC-e though a couple times strange things happened on Vircurex and Cryptsy that required contacting support. Both were quickly resolved though. Haven't yet tried Crypto-trade, Vault of Satoshi, Cryptonit, MCXNow - this is gone right?, Bitfinex, Kraken, upbit, Coins-e, etc, etc.
I really want the NashX concept to be further refined.
http://nashx.com/About