While playing around with Google's new calculator/unit converter,
I had a major epiphany that will undoubtedly advance rocket
science greatly:

The very same reasoning that allows Isp to be expressed in "seconds"
permits the energy content of fuels to be expressed in "feet!"

It's amazingly simple: if [Isp] = [lbf]/([lbm/s]) = [sec] then,
obviously, [energy content] = [ft][lbf]/[lbm] = [ft].

Q.E.D.

And it needen't be limited to rocket fuel, of course: we can
confidently look forward to the day when cans of sardines will
provide nutritional information not in "calories per serving" or,
even worse, effete things like "kilojoules per gram," but simple,
honest "feet."