Hmm, let me see.
CNN, ESPN1/2/U/News, NFL, MLB, Tennis, NHL, NBA, Golf, The 101, Spike, USA, Syfy, FX, Comedy Central, MGM, Universal HD, Smithsonian, Bravo, Nat Geo, Disney, Disney XD, Nick, ABC Family, QVC, MTV, VH-1, BET, Palladia, CNBC, Fox News, Fox Business, and then none of the premiums or regional sports channels as far as I know.
BBC-America does a 14:9 compromise like the Discovery channels. Beyond that, I don't know.
DirecTV broadcast QVC in HD?