I've been spending my spare-time contemplating a diagram with the needed buttons, knobs and various chips for turning the floppy drive into a complete instrument with a casing.
It looks like this (click for full size):

The first thing I've added, in the lower left corner, is 3-pole switch which cuts the connection to the power supply, turns off pin 14, and has an LED for letting one know when the bastard is turned on.
To the right is two switches directly connected to the floppy-connector-cable - one to 10/5 for turning on the motor, another to 18/9 for the direction of the stepper motor.
Above is a 555-timer IC, with resistor- and capacitor-values that makes the timer generate pulses in the 60-180 bpm domain. I found these quite useful for music-oriented tempi. I might experiment with the values when I get this converted to the real world.
A 2-pole switch lets one choose between the 555-pulse or a temporary push-button for one step at a time (this one I'm not sure if is correctly wired up?)
In the top left corner is another 555-timer. The fixed values of the components should generate a ~40 kHz signal.
This signal is meant for the bias-signal, which should erase the disk given a high enough amplitude.
I found an OP-AMP IC (TDA2822) which should be good for stereo signals. I want to build 2, one for the input signal, one for the output.
Given the fact that the heads on the FDD takes the input signal through the same lines as the output, I've drawn a 3-pole double throw-switch for the stereo signals plus the ground line. It lets one decide wether to record to the disk or play from it.
The last thing I've added is 3 LED's for the digital outputs on the FDD-cable, they should be lit when the drive detects the track 0 position, write protection I/O and Disk Inserted.
I'd very much like to receive feedback on this diagram! The OP-AMPs aren't yet drawn completely. I guess it should be quite straight forward.