Flamingo is a beautiful, native instant messaging client for OS X that supports Hangouts/Gtalk, Facebook, and XMPP.

Highlights:

• All-in-One design. Buddies, conversations, and chats in a single window.
  
• Multiple, detachable chats in a single window.
  
• Inline previews for images, videos, and tweets. Supports CloudApp, Droplr, Instagram, and YouTube.
  
• File transfer via direct connection (compatible with Messages, Adium, and other clients), CloudApp, and Droplr.
  
• Reply to messages right from the notification bubble in OS X 10.9.
  
• Full conversation history browser with fast message search and many filtering options.
  

• Fix crash when using the New Message pane (Command + N)
  
• Fix crash when loading new messages