Old News
My friend and I designed and built him some shelves. The design is pretty simple: 3/4" birch plywood for the carcase and shelves and some birch lumber facing to hide the plywood edges. Here's the design:
Original Design

The two bottom shelves sit in grooves (dadoes), and the smaller shelves higher up are adjustable. The top sits in rabbets in the side pieces.

A little ways in to the project, we changed the design slightly to set the front of the shelves back from the front of the case a little bit - it looks much better this way.

We got our plywood and lumber from Boulter Plywood in Somerville. They were a little more expensive than other places, but considering they're only a few minutes away by car, the convenience of not having to drive on the highway with sheets of plywood on top of my car far outweighed saving twenty bucks. The folks there were quite nice, and were happy to make a few cuts for us on their nice big table saw.

We set to work cutting the plywood to size, and then routing the grooves for the shelves, vertical divider, and top. Notice, too, the notches in the side pieces at the bottom - these fit over the molding in my friend's house:

Notched Sides

Here's the carcase all glued up (you can also see two of the four clamps I got as payment for the project):
Assembled Carcase

In this closeup view, you can see the dado that holds the vertical divider, the holes for the pegs that make the small shelves adjustable, and the 1/2" that the shelves are set back from the front:
Vertical Divider Dado

I ripped a bunch of long strips of birch lumber on the table saw, cut them to size, and glued them to the face of the shelves:
Gluing the Face Lumber

After the glue dried, we stained and finished the shelves (with Bartley Gel Stain and polyurethane).

Check it out (the first picture was pretty bad, so I had to adjust the contrast so you could make out the shelves - it's still pretty bad, but you get the idea):

Finished shelves

Finished shelves