This Cargo Cart is a versatile little puppy: you can attach it to the seatpost of your bicycle with a clip on the handle, or use it as a hand cart - it can haul a lot, and a bungee cord can add some stuff to the top on the lid. I use this regularly to carry 40 pounds of water from an artesian well in the Dundas Valley, but it can do groceries, trips to the beer store, and even stand-in as a make-shift wheel-barrow to carry soil.
It's an all terrain vehicle for the human powered. Beats a bundle buggy in mud anyday. Snow banks crumble under the 20 inch bicycle tires. I borrow mine from Mac Green at McMaster. I'm not sure where they ordered them from, but I found this Canadian site that makes them here.