Here is the Tailgater iPod Sound System from Ion. The System consist of a amplifier, audio inputs, docking station for your iPod and speakers in a box.
The Tailgater works with most iPod and comes with inputs your microphone and other gadgets. The box has a carrying handle for mobility and a built-in battery that gives up to 8 hours of power. The Tailgater is available at Ion for approximately $200.