My parents needed a small bookshelf for their apartment.  My quick solution is to use up scrap materials I have from my last project - the king-size platform bed.  I came up with a scaled down version of a wall-size bookshelf I built about a dozen years before. It's a sturdy and simple design that can handle heavy loads, and can be built in a weekend.  Using left over birch plywood, some poplar pieces for horizontal bracing, and some mahogany for trimming, the following is what I came up with for this simple bookshelf.  The completed piece was finished with polyurethane/tung oil for a natural-finish protection. 

Pieces cut to size.

Edge trimming of plywood pieces.

Fit check of the basic shelf - frontal view.

Top shelf trimmed with mahogany.

Backside view with upper and lower horizontal braces.

As an after thought, a middle shelf was added.

Typical plastic supports for the shelves.

Completed shelf with three coats of protective finish.

The assembled shelf at my parents apartment.