Scott Aaronson's lecture serious Quantum Computing since Democritus is brilliant - fascinating and hilarious. If I had been taught by this guy at university I might still be in academia. A quote:
Oracles were apparently first studied by Turing, in his 1938 PhD thesis. Obviously, anyone who could write a whole thesis about these fictitious entities would have to be an extremely pure theorist, someone who wouldn't be caught dead doing anything relevant. This was certainly true in Turing's case -- indeed he spent the years after his PhD, from 1939 to 1943, studying certain abstruse symmetry transformations on a 26-letter alphabet.
The sheer range of material just stunning too, and there are lots of in-jokes for those with a passing familiarity with the subjects covered. Plus really smart people like Greg Kuperberg and Bram Cohen read his blog. (And he uses the same hosting provider as me.)