Make:

Will O'Brien posted this short how-to on Hack A Day because he says the site gets quite a few hits on posts about the Bose SoundDock portable speaker system. On my site, Street Tech, the review of the SoundDock also gets lots of traffic, so there appears to be a lot of SoundDock enthusiasts out there...

There is a solderless way to hack an aux input for the Sounddock.

(1) Go to Wal-mart (or elsewhere) and buy the Griffin Dock Adapter for iPod Shuffle (~$20) and a Belkin Speaker and Headphone splitter (~$4). (The Belkin splitter is needed in order to fit properly over the Shuffle plug on the device, but other cables/adapters might work.)
(2) Remove the existing adapter plate and replace it with the Dock adapter.
(3) Set the switch to speaker. (Very Important!)
(4) Plug in one end of the Belkin adapter and you are ready to go! Any input signal automatically activates the Sounddock. Now you have a fully functional female and male stereo headphone input for your Sounddock.

-->Total cost ~$25 and no soldering required.

Hack A Day - Link
Street Tech Bose SoundDock review - Link