So I ended up buying an Arduino board for my art class and I'm pretty sure it's going to end up gathering dust after we're done with it. But I'd like to put that thing to use and came across an idea that I'd like to try. Would it be possible to create a program that can make LED's light up when you get new mail in GMail?
If you have a Mac, you can use Gmail Notifier and write a plugin for it. All the plugin would have to do is send a message out the serial port for the Arduino to turn the LED on and off. http://mail.google.com/support/bin/answer.py?answer=25749&topic=13383
Here's a different project for Linux, likely easy to modify: http://gmail-notify.sourceforge.net/
This project is for Windows, might be useful: http://johnvey.com/features/gmailapi/
Or you can write a program that can talk to the serial port to control the Arduino, and open TCP connections to Gmail's POP servers and detect when there are unread emails. With an Ethernet Shield, you wouldn't even need to connect the Arduino to a computer.