Booker
I'm particularly enjoying James Booker's jazz piano album, Spider on the Keys (iTunes).
iTunes makes it possible for me to run into James Booker's music. I don't go to music stores much, and rarely by anything when I do; it seems too risky. I'm not a big jazz fan, and I don't even know what barrelhouse is or exactly what stride sounds like -- and these, it seems, are the things Booker does.
The free samples at iTunes help a lot, and the immediacy helps even more. In a world where I seem to need to plan for two weeks to buy a pair of trousers, getting music has to be fast or I just won't do it.

Steve Johnson in The New York Times cites curatorial culture -- being able to exchange ideas through blogs and playlists -- as the most underrated idea of 2003.