None that grabbed me.
ii) Broadcast anniversary
26 August 1991: first broadcast of the so-called 'Pilot Eisode', the first mounting of 'An Unearthly Child' which was not shown in November 1963.
iii) date specified in canon that I should have noted two days ago
24 August, 79 AD: Vesuvius erupts, destroying the city of Pompeii, as witnessed by the Seventh Doctor and Mel in Big Finish audio The Fires of Vulcan (2000), and by the Tenth Doctor and Donna in The Fires of Pompeii (2008).