Yobit.net is one of the most popular cryptocurrency exchange site, opened in start of 2015.
They have almost all cryptocurrencies on their sites which can be traded, user-friendly interface, full trade page at the screen without scrolling, immediate cryptocurrency deposit / withdrawal.
You can deposit/withdraw USD, EUR, RUB and other main currencies. also, Yobit have few fun games like dice and Yopony where you can play with your currencies.
Yobit cares about safety of their service and they have: two-factor authentication (Google Authenticator, email),file systems encryption, SSL, anti-ddos, intelligent system of queer transaction analysis and blocking, real time encrypted data backup, cold/hot wallets.