I would think you can carry lots more and easier with one of these "garden carts".

http://www.norwaycarryall.com/carryall.html

We use one of these to haul horse manure to our compost area. It hold a LOT of weight and is tough as nails. The big wheels roll over bumps and curbs easier too. Note that they offer "thorn-resistant" wheels too.

It won't pull behind a bicycle or similar though.

I also have one of the aluminum folding Foldit carts that the same web site sells. I sometimes use it to help haul gear longer distances when out camping. Though it folds nicely, it is not NEARLY as tough as the plywood version.