CLiCk Speak Talking Browser Extension
The CLiCk Speak extension is an easy to use talking browser add-on for Firefox. At the press of a button, CLiCk Speak will read the contents of a web page that you have highlighted, or it can read the contents automatically. You can choose to access CLiCk Speak through the context menu, or via the CLiCk Speak toolbar.
Also see FireVox which is a more advanced free talking browser extension for Firefox.
