What to do with old iPod/iPhone Docks? I-Wave Receiver
The I-Wave receiver is a Bluetooth dongle that connects to your iPod or iPhone dock in place of the device. If you have upgraded to an iPhone 5, this is a great workaround to still use your previous 30 pin dock with a new lightning connector device. While you could splash out more cash for the Apple 30 pin to lightning connector (priced at US$39) and end up with a monstrous looking tall device, the I-Wave provides a more elegant and cheaper solution for a Bluetooth speaker system.
The I-Wave receiver connects to your iPhone or other music playing devices over bluetooth. It is available for US$19 from Amazon. After pairing your device, you would have the option to output your music through the I-Wave device. Initial reviews highlighted that the music quality while not exactly top notch, is fine for general listening. As for the range, the device would need to be in the vicinity of around 20-25 feet, around 6 meters. Bluetooth generally has a low power consumption so the additional drain for this on your device would not be too significant. One drawback is that you would not able to charge your iPhone or iPods through the dock. Lastly, due to the Bluetooth protocol of ADCP being used, control buttons on your dock other than volume would not work.
At the price of US$19, I feel that its a useful device for those who have upgraded to the new iPhone 5 or iPod and would want to continue using their existing dock. It is also great for those who had migrated to Android phones as Bluetooth is a universal protocol. A similar device is the CoolStream Bluetooth Receiver, and you can read user reviews here.
Android docks are actually few and far between, and with old iPhone 30 pin docks going on discount, this might be a good time to score yourself a Bluetooth wireless speaker system for cheap. One dock comes to mind: The Altec Lansing IMT320 30-Pin iPod Speaker Dock which provides pretty good sound quality from US$49. It has pretty good reviews around the web for its sound quality and affordable price. Pair it with the Bluetooth adapter above and you get yourself a bluetooth wireless speaker set. 
With Black Friday Shopping Season coming up in the United States, I am quite sure last-generation iPhone / iPod docks would be significantly discounted and getting it plus the I-Wave Receiver might make quite a bit of monetary sense. The wireless Bluetooth feature might be a boon to those who need to keep moving about as you can continue to use the phone while streaming music.