Speakerfone is coded in Applescript, designed to assist disabled people or those that want to have fun with OS X's built in speech synthesis. It simply displays a window with a text box. You type in the text box, press return, and your computer will speak whatever was typed in the default voice (Set in Speech Preferences pane). Repeat.
Allows you to continue typing while the previous text is being spoken, so that combined with a simple, keyboard-only operate-able interface make it good for real-time speech synthesis.