To give my students a little appreciation for their elders, I’ll demonstrate for them how to use a slide rule. Though I have my own slide rule which I can pass around the classroom, demonstrating how to use a slide rule is a little cumbersome since they don’t have their own slide rules to use.
I recently found an applet to make this demonstration a whole lot easier: https://code.google.com/p/java-slide-rule/
Mean Green Math 
Bonus: They might get a feel for logarithms as well.
They’re fun things to play with. I have a neat toy six-inch one I got as an undergraduate, and then a real one I bought in a university convenience store in Singapore.