Wooden CD Holders           

Gosh, this is simple, it could be used as a design in an exam, easy to remember and easy to make. It has no moving parts. It looks like someone turned a bottle shape on a woodwork lathe and then cut slots out of it the same thickness as the CD or Game packet. The bottle neck acts as a handle. Good design eh? Do you know you could use a router for cutting the slots, check it out here
Another simple one. A plank of wood with a short piece dovetailed at each end, one to give it an angle so the CD's tilt backwards and don't fall over, the other (at the other end of the plank) to stop the CD's falling off the plank. The little bit going up the back is to align the videos and stop them falling over the back. I think the whole thing is varnished and to see other finishes click here To see a range of joints, click here . Just think it would be easy to make this little beauty out of moulded plastic. To see injection moulding, click here

This is it, a crossed halving joint.

Look opposite to see what I'm

 talking about.

This is an interesting one, (well it is to me anyway). It looks like MDF that has been veneered using both wood or laminate (like laminate floors) and paint (the blue/grey bits). I reckon the shelves are held in position by the crossed halving joint and the sides are fixed to the shelves using KD (knock down) or QA (quick assembly) fittings. Look here to find out what a veneer is . Look here to look at man made boards (MDF is one, medium density fibreboard) . And look at the bottom of this page to see a variety of KD and QA fittings suitable for man made boards. (Reckon numbers 3a and 3b and number 6 could be used for joining this CD rack
Looks like a solid wood set of shelves which have been bought FLAT PACK like the ones above, and have either been put together using fittings like those shown previously, or by using real joints such as stopped housings. The back I think will be ply or hardboard which is coated with thin laminate to make it look like wood.

Yep you are right it is a Stopped housing joint and it could be used for fitting the shelves into the sides.