Fonix VoiceAlert 1.0.2
the author of this app says:
This scheduling assistant talks to you from your choice of 11 voices. It organizes and reads upcoming appointments and tasks aloud. Events are displayed using full graphical screens, with three pre-installed skins. If another application is active when an event occurs, a pop-up window appears as the top window, your customized chime sounds, and your preferred voice speaks the event.
TimeTalk Alert includes a digital clock that announces the current time in quarter, half or full-hour increments.