Best Bitcoin Wallet / Exchange Service -- USD/EURO/LTC/BTC

[Sioux]

Looking for a (free) BTC LTC EURO USD Wallet

that allows you to store BTC LTC EURO DOLLAR
and lets you exchange these currencys immediately with trading partners

you place your Unit
your trading partner places his unit

after both placed their units it gets released ASAP automatically

Example: I place 4 BTC
my partner places 70 LTC
both confirm and they get sent out immediately and arrive in a few minutes
in the partners wallet


Who offers this service?

Ripple.com?