yes, I remember watching the tv special "the making of the 777 -- the world's most advanced airliner" and they had a short segment on the minimum takeoff speed test.

for that test, they bolted a Very Large wooden (oak?) block to the bottom of the tail where it would strike.

they also showed the test of braking power where the takeoff is aborted at maximum allowable speed -- at the end of this test the tires burst into flames b/c the heat of the brakes and they had to sit there waiting for the amount of time it would take a typical fire crew to get to them at the average airport. pretty impressive.

I think these were done at an air force base out west, with like a 14,000 ft runway or so.