Once upon a time I found some audio of John Gielgud reading the sonnets, but complained that it was streaming only, not downloadable, and thus I never got to listen to it.
Chris Hughes just sent me this pointer to his LibriVox recordings of the sonnets, which are indeed in MP3. I've downloaded a bunch (they are grouped 10 to a file) but not yet had the chance to listen.
Also in Shakespeare Audio news I found an intriguing link to Shake5, and I'm still trying to figure out exactly what it is. Among other things it's 84 hours of recorded Shakespeare, which is cool. But it also appears to be some sort of CD-ROM hosted database complete with the text of the plays all synced up to the audio? It looks like it may have been for sale at one point but is now transitioning over to be a free download. Anybody know more about the project?