instead of a concrete slab-- genius! And great drainage. Great idea for garden shed or even the chicken coop. Wouldn't have to worry about foxes digging in to the coop and it would be cheaper than concrete and easier to clean than a plywood floor.
Millers outbuilding - A great selection of design ideas for potting sheds. Lots of inspiration here for the DIY enthusiast. The one pictured has at least 2 good ideas I like: a covered entry and a sliding barn-style door for equipment like a wheelbarrow or garden wagon.