The PLANET25 server was conceived to be an example of good PC modding.  The old HP server case was decidedly not designed for modern computer parts, and was heavily retrofitted.

The server got a much-needed upgrade in February of 2008 with the replacement of its 1.266GHz motherboard with the board from a Dell PowerEdge 1600SC server, using a 2.8GHz processor.  Cool.

Here's the completed case.  The left side has (top to bottom) the activity lights, power and interior light buttons, status display, and usage meter.  The right side has (top to bottom) two different fan speed controllers, a DVD drive, and two vented drive covers for air intake.
The status display is a prorammable VFD we've set to alternate between server name, uptime, free RAM, and free disk. 
Each fan speed controller is a four-knob device that allows fine-tuning of the fan speeds to achieve a balance between cooling and quiet. 
Here's the CPU utilization tachometer.  The busier the server, the higher the number.  It doesn't get too high very often, since sharing files is a fairly simple process for a computer.  This movie shows it fluctuating all over the place as a bunch of files are transferred to the hosted web server.
The main attraction for those unfamiliar with PC modding: the window.  Two blue cold cathode lights on the top and right side give it the blue glow.
Removing the cover yields this view.  The power distribution box in the upper right lets custom-length cables be used to keep things neat.  The big 120mm fan, middle right, is running at low speed to eliminate noise, but it still pushes a fair amount of air because of its size.  The circuit board at upper right originally used a proprietary ribbon cable to connect all front panel functions to the unique motherboard... of course, a lot of soldering and cutting let it be used now.  You can the two blue cold cathode light tubes at the top and right.  The processor's heat sink and fan has a radioactive symbol on it, and is illuminated by blue LEDs whenever the computer is on.
Here is the SCSI controller cards used to access storage devices.  This card is a SCSI RAID controller, and connects to three hard drives set up as a RAID5 array.
The rear of the case has some more stuff to look at.  The fans have laser-cut radioactive designs on them, which are secured using blue LED fan screws.  A blue cold cathode light behind the fans lets their insides glow.  In addition to the usual cables, it has a serial cable for the tachometer.  The cable end is too large to go through a slot cover, so fortunately we had a removable panel to the left that we could cut a perfect-size hole in.
What's on the other side of the case?  Guts!  The power supply and the disk array are some of the major components here.  Another light tube makes the air intake vents and rear fan outlets glow.
Here's a close-up of the custom-built RAID5 disk array.  There is a 120mm fan in front of them that forces air through the spaces between them, keeping them cool and happy.  Little rubber grommets in the screw holes prevent any metal-to-metal contact; this means the drives' vibrations can't reverberate.  The case's walls near the array are covered in sound absorbing material.

Really bored?  Here's a list of the work done to the server through the years.