The Rock Trading Ltd, a Malta based company, has been in operation since 2007 and traded its first BTC on June 1st, 2011. It's one of the oldest Bitcoin exchanges still alive.
The Rock Trading is also an official Ripple gateway.
The Rock Trading, in a partnership with GreenAddress, is able to provide instant multisig confirmations on deposits and withdrawals.
On The Rock, the following pairs are traded: BTC/EUR, BTC/GBP, BTC/USD, BTC/XRP, EUR/DOGE, EUR/XRP, LTC/BTC, LTC/EUR, LTC/USD, NMC/BTC, PPC/BTC, USD/XRP.
The Rock Trading offers huge and quick discounts: fees can go down from 0.50% to 0.075%
The exchange offers also a prepaid card that can be funded with the balances held online, and used in many shops.
Some info on its Bitcointalk thread.