Spike HD, Comedy Central HD and MGM HD. As far as LiL HD channels, I've found that the OTA tuner on the 722 does a great job at getting a good signal. It is noticeably stronger than connecting to the OTA tuner on my Vizio HDTV.
As an DishHD Only package subscriber, I want Spike HD so I can see ST:Voyager again 2 times a day, Disney HD for the kid (and apparently lots of real HD!), and Travel channel HD.
(Yes, I know 2/3 of these are not even on the slate.)