haha...
I find that as a physics student, I use mostly SI, and then some other, more strange units, as you've said...but in my non-scientific life (yes, it's slowly disappearing
), I use old imperial measurements all the time. I think about things in quarts and in gallons, and in miles, feet, and inches...and miles are quite convenient units in that it's the distance you go when traveling a reasonable speed in a car in one minute...so, when you don't live in the city, the amount of miles to a place is pretty close (as opposed to kilometers) to the amount of minutes it takes to get there.
Not that that's a very strong argument for keeping the system, but it's about the best, practical use I can think of.