A few days ago I got a little idea - I use Adium (adium.im) as my MSN client and if I have it minimised I can't see the status of my contacts. It is also a problem when I am lying on a bed and watching a movie - I can't see if one of my contacts is online or is currently talking to me (I am too lazy to get up and check). So I decided to make a realy simple thing - AdiumDuino - it is actualy a simple box with 9 LEDs (each of my 3 most commonly used contacts has 3LEDs - two LEDs show the current status, and one shows if I have any unread messages from this contact). Here you can see how it looks like and how to make one for yourself.
On the image above you can see a key - this key is used to turn the screensaver on/off (without the need to enter the password), and nine LEDs. Each contact has a blue LED (if I have any unread messages from this contact), yellow LED (the contact is currently away/busy) and a green LED (the contact is available). If all LEDs are turned off then the contact is offline. There is also a piezo speaker inside the box - it makes noise when there are new unread messages from the "chosen contacts". This is because I sometimes have the sound turned off and don't hear that someone is trying to talk to me.
From the image above we can see that the contact labeled S is offline, contact labeled with D is online and the contact labeled with T is busy/away.
You don't need much. You will of course need arduino microcontroller (arduino.cc) Nine LEDs, three resistors (3x100 ohm). The green and yellow LEDs in my case needed a 200ohm resistors and the blue LEDs needed 100 ohm resistors. You connect the + pins of the LEDs to the digital out on arduino and the negative pins through the resistor to the ground. If you would like to have the key - you will need a key switch and a 10k ohm resitor and you will also need a piezo speaker (you can find one practicaly anywhere). You will find the guides how to wire the LEDs and the switch on the arduino's homepage. You will also need a box tu put the LEDs and arduino in. I recommend that you find something that looks a little better than my box.
The entire computer side is written in applescript (because it runs on every mac and most applications can talk to it - including Adium). On the PC you will need the Serial Port X (you can find the link to download it inside the app package). The source code for the mac and arduino is included in the download package.
The application is realy simple. It basicly checks the status of your contacts and sends the command to turn on/off the LED to the Arduino via USB port. Because of that you will need the USB connected to your computer and you can't use the digital pins 0 and 1 on standard Arduino boards.
Here is the actual download package:
If you have any qestions - please send me an email (my email adress is located on the support page).