Building a Metronome
Mathematica, 26 bytes

Pause[Beep[];60/#]~Do~∞&amp;


Do is normally used as a "for" loop in the narrowest sense: repeat this piece of code for each i from x to y... or even just repeat this piece of code n times. Instead of a number n we can give it infinity though to create an infinite loop. The loop body is Pause[Beep[];60/#] which is just a golfy way of writing Beep[];Pause[60/#] where # is the function argument.

If it's admissible for the solution to blow up the call stack eventually, we can save one byte with a recursive solution:

#0[Beep[];Pause[60/#];#]&amp;