A trip to our local DIY store left us depressed at the high cost of frankly flimsy shelving products. Out in the parking lot we spotted some "apparently abandoned" pallets and we helped ourselves to a few hoping to at least get the boxes off the floor and deal with building proper shelves later. Midnight musings came up with an idea to solve our shelf problem for almost free. This instructable is more about the idea than the actual construction. You have many options to use pallets as shelves but here is how we did it.
Step 1: The math
You have three choices. (1) You could use the pallet "as Is" which is 40" X 48". This would work well if you had access to both sides of the shelves. (2) Cut the pallets in half to create two shelves 20" deep X 48" wide. or (3) Cut them in half you have shelves 24" deep X 40" wide. We chose this option because , if you look at the construction of a pallet, you will see that this is the easiest option in terms of additional bracing and ease of cutting. Two additional factors were: (1) These shelves are up against a wall and 40 or 48 inches is too deep to use full pallets and (2) 10 feet (120") long fit our floor [three pallets X 40"] and 12 feet (144") did not. Anyway this project could work from 1 pallet wide to ?.