An experiment using Ruby and an Arduino to notify the user about unseen email messages.

arduinoNotifier.pde

const int led = 3;
boolean active = false;

void setup() {
     Serial.begin(9600);
     pinMode(led, OUTPUT); 
}

void loop() {
     if (Serial.available() > 0) {
          if( Serial.read() == '1' && !active ) {
               fade(led, 0);
               active = true;
          }
          else if( active ) {
               fade(led, 255);
               active = false;
          }
     }
}

// If brightness is more than 'half' of 255, is fadeOut.
void fade(int pin, int startBrightness) {
     int fadeAmount = 5;
     int brightness = startBrightness;
     
     if ( brightness > 125 )
          fadeAmount = -5;

     while( brightness >= 0 && brightness <=255 ) {
          analogWrite(pin, brightness);
          
          brightness = brightness + fadeAmount;
          delay(25);
     }
}

serialMailNotifier.rb

class EmailAccount
	require 'net/imap'

	def initialize(user, password)
		@imap = Net::IMAP.new('imap.gmail.com', 993, true)
		@imap.login(user, password)
	end

	def newMail?
		new = 0
		new = 1 if @imap.status("inbox", ['UNSEEN'])['UNSEEN'] > 0

		return new
	end
end

class SerialWriter
	require 'serialport'

	def initialize
		portStr = "/dev/ttyACM0" # Probably you'll have to change this. :/
		baudRate = 9600
		dataBits = 8
		stopBits = 1
		parity = SerialPort::NONE

		@port = SerialPort.new(portStr, baudRate, dataBits, stopBits, parity)
	end

	def write(content)
		@port.write(content)
	end
end

class Notifier
	def initialize
		@writer = SerialWriter.new()
	end

	def setMail(user, password)
		@email = EmailAccount.new(user, password)
	end

	def run
		while true do
			@writer.write(@email.newMail?)
			sleep(600)
		end
	end
end


# Usage -------------------------------------------------------

notifier = Notifier.new()
notifier.setMail('your.email@gmail.com', 'yourBeautifulAndSecretPassword')
notifier.run()