OK, I have a couple. We do park 2 cars in our garage, so our storage is on the walls. The cabinet in the first picture is for basketballs, tennis rackets, etc.http://img.photobucket.com/albums/v4.../garage1-1.jpg
These shelves are over the garage door - when the garage door is open, you can't even see them.http://img.photobucket.com/albums/v4.../garage2-1.jpg
We also have shelving along one wall - wooden frames we bought at Menards, with plywood sheets for the shelves themselves. I think they're 2 feet deep, and at least 8 feet long.
If I was going to use my garage just for storage, no cars, I would build big shelves along every wall, and stack plastic tubs in the middle, with everything labeled so I could find it.