Some bikes designed to transport different cargo, inspired by sounds_sound's tiny bike-house post.
I've sort of wanted to do more biking, but my state is very seasonal, and when the warm weather hits a pedal bike just can't compete with my motorbike. I still maintain a small bit of bicycle envy though.
These bikes are quite common in the Netherlands. People use them to transport small children, dogs, large loads or just to get somewhere. Especially popular among young parents nowadays.
I have had a Yuba Mundo for a few years now and it has been great. While it is very heavy, it moves along well and can sure carry a load. It transported my son to day care and me to work everyday for the last two years and allows moderate sized grocery trips. I live in the South West US so I get to use it year round.