I have said this on the sport forum, but I think that it's really worth bringing up:
New world champion, new WR - 9.58. 9.58!!!
I remember Maurice Green getting 9.79 as a new WR, only ten years ago. Bolt just destroys anything that's gone before, it's astounding.
I remember when getting around the 10 second mark, dead, would put you in medal contention in most races, and going under was special.