Some of the best apps available take existing mobile phone functionality to the next level, and all of our Top 5 featured here are outstanding examples. Our No. 1 choice is WhatsApp Messenger. The attaching of multimedia to messaging alone is a good enough reason to get this app. However, you can also chat and group chat as much as you want globally without paying into the mobile networks’ SMS cash cow. WhatsApp Messenger is available for iPhone, BlackBerry, Android, Windows Phone and Nokia — and all of those phones can message each other. 
