A couple of years ago I considered converting my bike to an
Xtracycle, but the reality is that a ride to the nearest grocery store is a sixteen mile trip (down a very curvy two lane road) and my job, at the time, was 20 miles away, so the people at the bike shop actually talked me out of spending the money. It seems more practical for people living in a town or city.
Here's a picture of an Xtracycle family vehicle
This Xtracycle is being used to take 120 lbs of stuff to the Goodwill:
