Who likes cables? Nobody likes cables. They limit your range of action, they get tangled up and they are simply ugly. Thats why we invented wireless technologies, like bluetooth. So lets get our hands dirty. What you need for this simple demo is:*An Arduino (UNO, Mega, Duemilanove, etc.).
A led. A bluetooth module (You can buy it on Dealextreme or just do a quick Ebay search) A USB Bluetooth dongle in case your computer doesn’t have built-in bluetooth.