Instructables employee Aleator777 has written an in-depth guide to creating an email notifier with a Pi. It checks a Gmail account and then lights up if there is new email. It’s quite a complicated tutorial and even uses laser-cut wooden parts as a case, but you don’t, of course, have to go that far with it – take a look at the code and see if you can build a simpler version with a breadboard and LEDs! Read it here