Whew! After that in-depth treatise from Ray on the care and feeding of relays, I don't want to hear any more grumping about my posts being long. Good thing he cut-and-pasted it. 
Back in the "Old Days" (before transistors and integrated circuits) there was a fair amount of "Relay Logic" being designed - circuits that depended on relays and primitive sensors to make "decisions". But the coolest ones I ever worked with were telephone switching systems for rotary dial telephones (I'll bet Danny has seen a bunch of these, too, hopefully in museums).
Mechanical Telephone switching (stepper) relays were pretty cool buggers..... They had 10 horizontal wafer switches stacked up 10 layers high in a vertical column, and at their center was a rod that handled the wiper (the arm that makes the relay connection in those diagrams up above). The rod could be elevated in steps to a particular wafer switch and then rotated in steps to a precise position on that switch. Remember, rotary dial phone, here, and also remember that the rotary dial itself was nothing more than a switch that closed (with a short pulse) for every number you chose: dial 3 and get three pulses, then a space while you dial the the next number for those pulses and so on.
The first digit you dial makes the first stepper go up as many levels as you dialed ( 0 - 9 ) to that wafer switch. The next number you dial makes the stepper rotate around that wafer switch to the dialed position (0 - 9). The next number dialed goes to the next stepper and makes it go up like the first to whatever number you dialed and so forth. You needed 15 stepper relays in the system to allow for international direct dialing (all determined by the country code and then the number). This system took, as input, whatever number you dialed on your pre-touch-tone phone and converted it from an analog (pulse) input to a pseudo-digital representation that the switching system could route to get you to the number you dialed. All the system did was switch your "line" to another line determined by what series of numbers you entered.
Pretty cool, huh?
Here's a very cool (and very old) video I found that 'splains it with pictures, so come with me, now, to those thrilling days of yesteryear when everyone had Bakelight, Rotary Dial telephones (and let's thank the crew at the Bell Labs for dreaming this system up):