On the Internet, you can come across weird electronic stuff. I still can't remember how I came across the existence of circuit bending.
To make a long story short, circuit bending is a process by witch you modify the way a circuit should work, hoping for crazy or awesome results. To further your knowledge of circuit bending, check Wikipedia. The whole idea of making music using circuit bent devices was made more popular by Reed Ghazala.
Amazon and other fine retailers) but the most well known are the Speak series of toys by Texas Instrument in the early 80's. These toys had synthesized voice and had a large vocabulary.
I was recently able to get my hand on a really minty Speak & Read toy (even with the slip case). I knew I had to "bend" it. Since the required parts are switches, push buttons and potentiometer, it was nothing my trusty local part store couldn't handle. I did feel cheated on the normally closed push button... They are not commonly stocked so the only one they had was 13$... I'll buy one online next time.
I was lucky since everything worked out fine the first time. The reset button does it's job: since the results are almost always random, you might need to reset the machine after a while. The loop button and switch work together: you press the button to "test" your loop and when you find one suitable, you "lock it with the switch. The pitch dial is the best feature in my opinion. Slowing the pitch to the limit always makes it sound weirder.
While this was a cool project to do, unless you're a musician, you won't find much interest in this. I have fun with it from time to time and I am always amazed at the sounds that comes out of this thing, but I'm pretty sure I was the only to find it interesting. That being said, I'll probably keep it, even if they sell for quite a bit on ebay.