That is very cool!! To keep things in place, get some velcro tape and stick a piece on the bottom of items you want to stay put. If you are putting books on it, you could install a thin brass rod a couple inches up from each shelf to keep books in place.

I love that too!

We are planning a similar door to our furnace room. The door is partially visible from the front entry of our split level home.

Could you post pics/explain what kind of hinges you used?

Have you got a 'secret' compartment in the bottom part of the door?

When DH finally gets it finished, I'll post pics of my secret compartment in our closet floor! :>)

The hinges were the most difficult thing to figure out. I ended up going with heavy duty swing clear hinges (from Hardware Source and then carefully placed the frame trim so that it covered most of the hinges. You can see the barrel of the hinge protruding from the right edge of the trim in the first picture above. Note that to get the trim to fit down over the hinge, I needed to route out large notches in the back of the right side trim piece.

The other big difficulty was remembering enough of college trigonometry to figure out how much the sides of the cabinet needed to slope in at the back of the cabinet so that the door would be able to swing open. (In my case the answer was 12.5 degrees)

The total cost for this project breaks down as follows:
$150 - wood (2 10' 1x8 poplar, 1 4' 1x8 poplar, 2 10' 1x3 poplar, 1 4'x8' sheet plywood, 1 pre-primed paint grade door frame)
$90 - swing clear butt hinges
$100 - pocket screw jig kit

I don't have a secret compartment in the bottom of the bookcase, but I think I will put one there that will be accessible from the inside of the closet.

Very Cool!

Haven't used any of this stuff myself but it might be solve your keeping stuff from falling problem.

Here is a link that might be useful: Quake Hold Products

Excellent! I love really it, Bob. I love the unsuspected broom closet, and I love the idea of yet another "secret" or at least discreet, compartment. Will the door handle the weight of books, which in itself would help keep them in place? If so... In California, we didn't have shelves in doors, but the earthquake putty Ci Lantro points out kept antique vases safe on what should have been stationary shelves for decades.

Too cool! I have always thought secret doors and passageways were so fun and wished we had them in our regular old house.
Is it deep enough for books? I was thinking you could make a glass door for the top of the bookcase.

Would using magnetic strips (found at the craft store) work?