Soul Sides has a kind of collaboration with Michelangelo Matos, who recently gave a lecture at a conference in Seattle on the history of the guitar riff used in the song "Apache." The lecture was given without music; Soul Sides prints the lecture with Matos's permission, and provides links as well as the songs referenced in the paper. It's a brilliant way to use the MP3 blog format.
Here is the lecture, with links to the songs referenced in it (all downloadable -- you've heard many of them before, even if you don't recognize the artists or song titles).
Speaking of lectures on the genealogy of riffs and samples, check out Wayne Marshall's blog, Wayne & Wax. Marshall is, I believe, a professor of ethnomusicology at Brown, who writes about Reggae and Hip Hop sampling (I came across the blog while digging for information on Damian Marley for the previous post).
At the end of this post, you can listen to a streaming version of a lecture Marshall did at a conference, on the "Mad Mad" sample in reggae music. (See Reggae-Riddims website for more on "riddims"; it's the definitive website on the subject, it seems to me)
Marshall also links to the text of a similar (but not quite identical) paper he did at a conference in New Orleans here, if you'd rather read it.
Both lectures are about recovering the lost (or hidden) genealogies of sound samples. It's a very different way of listening to hip hop and reggae from the historically 'flat' way one tends to listen to the songs on the radio. It's also a little geeky, to be sure, but then Who Am I To Complain? (And: "How Am I Not Myself?")