The Pro Alarm Clock from Bellman and Symfon has a loud (100dB) alarm and strong vibrating bed shaker.  It also has a connection for the telephone line, so you can be alerted to phone calls, and an external input socket for connection to other Bellman Visit devices such as the mobile phone sensor or contact mat.
 
This model also has a night light, which provides enough light to see your way in the dark, without disturbing others who are still sleeping.
Mains powered, with backup battery (4 x AAA NiMH batteries installed
 
Cannot be used with the Bellman Visit system