I'd mention Bret Victor's work before (maybe Drawing Dynamic Visualizations?), but Bret cheats by writing a lot of amazing code for each of his talks, and most of the awesome comes from the code, not his (great nonetheless) ability as a speaker.
Then you have John Carmack's QuakeCon keynotes, which are just hours and hours of him talking about things that interest him in random order, and it still beats most well prepared talks because of how good he is at what he does. HN will probably like best the one where he talks about his experiments in VR, a bit before he joined Oculus (stuff like when he tried shining a laser into his eyes to project an image, against the recommendations of... well, everyone): https://www.youtube.com/watch?v=wt-iVFxgFWk
I'd mention Bret Victor's work before (maybe Drawing Dynamic Visualizations?), but Bret cheats by writing a lot of amazing code for each of his talks, and most of the awesome comes from the code, not his (great nonetheless) ability as a speaker.
Then you have John Carmack's QuakeCon keynotes, which are just hours and hours of him talking about things that interest him in random order, and it still beats most well prepared talks because of how good he is at what he does. HN will probably like best the one where he talks about his experiments in VR, a bit before he joined Oculus (stuff like when he tried shining a laser into his eyes to project an image, against the recommendations of... well, everyone): https://www.youtube.com/watch?v=wt-iVFxgFWk