WhatsApp, the popular chat app, now has a web version, though you'll still need your phone to connect to it.
The new web client basically mirrors the app on your phone onto the web site. To use it, you need to head to the WhatsApp web page, scan a QR code with the WhatsApp mobile app, then get to typing your messages from there. Right now, the web app's only compatible with Google Chrome in combination with the Android, Windows Phone or Blackberry version of the mobile app. iOS compatibility isn't available for now.