Voxer Walkie-Talkie PTT This app lets you talk to your friends as if your phone is a walkie-talkie, the only difference is that there's about a 5 second lag between the audio and that there is no maximum distance, which is great.

Viber : Free Messages & Calls This app lets you send voice messages and texts for free and just as easily as actually calling or texting someone.

Facebook Messenger Why bother wasting time checking statuses when you can have an entire app merely for chatting with people.