I asked on this list recently if anyone had come across one of the USB pendrive-sized ARM/ Android devices but with a headphone jack and got no response but it seems such things do exist already, or at least there is one such model, the MX3 RK3066.

http://www.ebay.co.uk/itm/MX3-Camera-8G-Android-4-1-Mini-PC-RK3066-Google-TV-Box-Player-Wifi-Bluetooth-NEW-/251254653914?pt=UK_Sound_Vision_Internet_TV_Media_Streamers&hash=item3a7ff1c3da

At ~70GBP its twice the price of similar spec devices that lack the AV port and the (likely totally useless) webcam so its a bit of a risky purchase for me until someone confirms that the AV port works with regular ALSA.

Should the temptation to get one of these overcome anyone, please let me know how you get on with the AV out under Picuntu (or whatever non-Android Linux distro you may install on it). If it works I suspect I won't be able to resist the novelty factor.