My husband recently bought a cargo trike. It is basically a large tricycle with a basket on the front, and a large flat platform between the back two wheels. My husband and father-in-law designed and built a very large and sturdy wooden box that screwed to the platform.
It also has two little benches in the back that my two older kids can ride on. My husband can now quickly take them on shopping trips, and to fun places like the pool and playground. Riding is much quicker, and you can cover more ground then walking. Our oldest is too big for either of our double strollers, but is not big enough to walk the five miles or so to their favorite neighborhood park ( round trip). At least not without complaining or being obnoxiously slow.
The benches are quickly and easily removable for large shopping trips. This morning he easily fit two weeks worth of groceries in there. It sure beats his old method of using large Rubbermaid bins on an industrial four wheel dolly. The box even has a locking lid that can keep the purchases from one store secure while shopping in another. The size lets us buy items that are too bulky or heavy to carry on the bus or under a stroller.
The size and weight of the bike keeps the speed down, but the three wheel design makes the bike more stable. It is certainly not as convenient as a car, but it makes life a little easer for us. We can be more independent , and it gives us a few more options with the kids. All in all I think Scott, and his dad Al, did a super job on the box, and I know well enjoy using it for years to come.