nice!
that trike transmission is the best ive seen yet! ive ridden a bunch of trikes and until now the best one had a differential on it like a car, but sadly the thing got skidded on so much that the teeth sheered off gears inside the differential. that trike looks great! looks like you can pedal even with one wheel off the ground, which is great when just fooling around on the things!
as for cargo bikes, i built a long john style bike a few years back out of a bmx and a step through, ill see if i can dig up some pics of it, as its currently in the possession of my buddy...