A mutifunctional Calculator

Ever thought that you could communicate with someone while the surrounding people think that you're simply using an every day tool such as the calculator. The idea came to me yesterday while I was desperately trying to make something to better my skills with PIC Microcontrollers and saw an article by Myke Predko. In that article he explained that an LCD(Liquid Crystal Display) can by operated only by two pins of the microcontroller, which allowed me to add a 4x4 button keyboard(enough for a calculator). But I thought that a calculator with mostly all the math functions is cheaper than 4 dollars(2 dollars for the PIC16F628A and the other for components and test board). So I said to myself: "What if it's a calculator that sends messages to other calculators of the same type! That would totally be worth 4 dollars!" So, here's how the idea was born. What I plan for the calculator is that, it'll have a button to enter "Special" mode. In that mode, the user could choose to use the calculator as a messenger or to perform special math functions (such as sine, cosine, root, power, etc..). As a messenger (the good part) the calculator will receive a maximum of 6(undetermined) messages from other calculators and send messages to other. Ofcourse, if the user already has 6
messages and receives a new one, the first of the those is deleted and replaced by the new one.
A message will be deleted right after it's been red. Perhaps when I make the basic structure of the calculator, I would add nicknames and block systems. I'm really excited with this and I hope that my idea will become reality. I also hope that the idea is not already developed or under development.
Share your thoughts about the idea, or even give me ideas about it!