Don't expect in-depth discussions for most of these though. The cases that you use can be more important than one might think. They don't do much electronically other than supplying the power to the components, but they do need to be designed well enough to allow heat to flow through them and out. They also need to be easily accessible and not cramped on the inside. The more expansion bays they support, the better.
Size is also important.
My pick for the best case is Addtronics' Server Tower case. Although it's pretty expensive, it will provide great cooling and a lot of expansion space. It has a total of 8 exposed bays, front panel pops off, side doors swing open, top pops off, motherboard tray slides out, it has space for at least 8 fans, it has air filters for the fans, and many other nice features. There is also a Mid-Tower version of this case. Other good cases are made by InWin, CalPC, and PC Power and Cooling.