I'm in the PL community, so talks by people like Gilad Bracha, Richard Gabriel, Guy Steele, Dave Thomas (the OTI founder), Christina Lopes, Simon Peyton Jones are really good. I saw a Bret Victor talk that wasn't really bad either, with lots of wit, though he seems to be a bit more subdued than I'm used to (which is fine, it is important to stay real to yourself as a speaker). I'm sure I'm missing many people in the list of good speakers.
Also, James Mickens in the systems community (and also a colleague at MSR) is really good. He tends to go off the wall a bit more, but that is just part of his rhythm.
The point of TED talks isn't that they're supposed to have a stand-up comedian's level of presentation skill. It's about captains of industry talking about their slice of the world.
Also, James Mickens in the systems community (and also a colleague at MSR) is really good. He tends to go off the wall a bit more, but that is just part of his rhythm.