Basement Closet Storage

Hi
When I redid my basement a couple of years ago, I thought I was being a hero and built a huge storage closet. However, as my daughter as reminded me nearly everyday, I screwed up. The shelves are 24" deep and stuff seems to get swallowed up into the back never to be seen again. What I would like to do is this - any help?

I would like to install 3 32" "box store" bookshelves (15" deep) against the back wall of the closet. Then, install another 2 of those bookshelves in front of the back ones on some sort of sliding rail(s) on the floor. What I am trying to accomplish is that when someone needs to get to one of the back bookshelves, they would slide one of the front ones over to reveal the back thereby allowing easy access to all "missing" stuff.

Hope I made sense.

Thanks