Usain Bolt's 100 meter dash world record in Berlin on August 16. 2009. 
I slowed down the footage by a factor of four and added some information about the intermediate time, distance and current speed. He had a reaction time of 0.146 (0.133 in the 200m final four days later) reached his top speed after about 70 meters (something between 12.3 and 12.4 m/s) and then slowed down, especially after about 93 meters. So he surely is able to run a bit faster still.
The data is from Berlin Biomechanics Project (http://berlin.iaaf.org/news/kind=101/newsid=53084.html) and should be quite precise. I'm not related to that project al all, I'm just doing this for fun.