When I was a kid, my teacher had one of these bells on her desk. She would ding it if we were being too loud and anyone talking after the ding got spanked. I got spanked a lot. A hack has surfaced that takes one of those bells and rather than wedging it in a first grade teachers bum, it connects the bell to your computer via USB.
The idea is that instead of those computer generated dings to tell you when you have new email, this bell will ding to tell you for realz. It seems that the virtual bell would do the trick just as well and you can mute the sounds if the dinging drives you crazy.
The USB bell uses an electromagnet to activate the bells dinger. Apparently, the bell is easy to build as well. You need a few parts and you need to have some soldering skills, have a bit of electronics understanding, and you don’t need to know much in the way of programming. Check out all the instructions here.