add an aux input to a stock radio

I'd like to add an aux input to my stock radio.  It's a single cd in a 2002 Ford Ranger Edge.  I'm wondering if there's any way I can do that, short of installing an aftermarket cd player.  I already pulled the deck out of the dash, and it appears there's an extra plug on the back beside the main plug.  I'm assuming it's for a cd changer?

As an aside, if there's any way to have an iPod dock, that would be great, otherwise, I'll just use a patch cable like what my wife's car has.