Yep, I had a whole post written on Aug 28, 1963, the day when Martin Luther King Jr. gave his 'I have a dream speech'. In my post, I spoke about his goals, his legacy and those of Daniel O' Connell and Gandhi, as well as focusing on speeches themselves: how vital for society they used to be; and how infrequent and, unfortunately, veritably redundant the are nowadays in our information-saturated world.
Instead writing out the whole thing again, I've taking the erasing as a sign; a sign not to do so. You do it! Think about those hugely influential speakers, what speeches do, and assess the need and effectiveness that such speeches would have today.