http://www.engadget.com/2008/03/10/cowon-q5w-does-snes-emulation-with-a-ps1-controller/If you're an owner or prospective owner of the Cowon Q5W, you're probably impressed with its myriad audio and video playback capabilities -- but did you know it can handle emulation as well? Apparently, since the device is based on Windows CE, it's fairly easy to get game emulators up and running on the 5-inch PMP. In the video you can watch a setup of what appears to be an SNES imitator playing both Donkey Kong Country and Super Mario Kart (two favorites of our SNES fanboy, Paul Miller, we suspect). The games are controlled by a decidedly non-Nintendo accessory -- a PS1 controller connected via USB adapter.
Without access to the dock connector through the SDK, we can't count on reliable 3rd party software that companies would be willing to invest in.
A keyboard (personal favorite), game controller, scientific sensors, gps modules, etc. are all possibilities, if only Apple let them be
