Do you an app called "Find my iPhone". This app will help trace your iPad if it's connected to a Wi-Fi. Try going on Apple Support Communities and look for a solution because this isn't common.
Your iPad serial numbers are engraved on the back case toward the bottom, as shown on an iPad below. The MEID and IMEI number (when applicable) are also engraved on the back of iPad (Cellular Models).
Not a great deal of use when the iPad has been stolen! I read the OP as saying that he knew the serial number.