Cuba has been using cargo bikes like the one's pictured above for many years now. Because they can't get car parts shipped in from the USA (also the reason you see such awesome 1950's cars still in daily use there) , they make do by re-purposing bike parts.
http://www.flickr.com/photos/brianail/14069310/
I used to work for a foundation that gathered up "useless" old bikes from around Vancouver and send them in a shipping container to Havana. The mechanics there took this entire container of random, used and discarded bike parts and turned it into as many cargo bikes as possible. Amazing mechanics with minimal tools!