Hi,
I also got my fingers on the iRig Keys. It is small, fits in the backpack and does what it is suposed to do.
http://www.thomann.de/gb/ik_multimedia_irig_keys.htm?gclid=CLPn4q6vk7gCFU2R3godlX0AEQ&sid=4196ac7b6f3a757ab38441d7042e5ac6
cheers,
Jan