Some components are found in every design, others are more rare. I’ve met designers claiming that digital constructions not including a PIC must be broken or trivial enough to implement using a single PIC. Still, there are some unique components out there.
For the engineer striving for a truly symmetric world, the WOM is a must. Signetics and National helps us there. For the apocalyptic individuals among us, Maxwell’s Nuclear Event Detector might be of interest. Connect it to trigger the closing mechanism of your bunker and you can sleep tight.
Still, the WOM comes with the most useful figure I’ve encountered yet (thanks to Reine for the tip): number of pins remaining / number of socket insertions.