I started with the Keira Knightley/Jack Davenport audio commentary on Curse of the Black Pearl (disc one), which was pretty damn sweet. Then I switched over to Dead Man's Chest, with the hopes of finding another sweet commentary.
No such luck (only commentary by Ted and Terry, the writers - disc one), but there is a whole slew of other really amazing features (disc two).
There's a cool 20-minute thing on Jack Sparrow's costume and props, which was cool, three 5-minute segments of "mastering the blade" for Orlando, Keira, and Jack, a feature on the bone cage, one on the kraken, and another on creating Davy Jones (Bill Nighy is so cool). Most of the features range from 5 to 15 minutes.
But, the most amazing of them all were two in-depth features on the making of the film. There's a 25-minute segment, "Charting the Return," on pre-production (and how the film almost died before it started) and an hour-long feature, "According to Plan," on the production (and more reasons the film could have failed tremendously).
It was VERY Lost in La Mancha, an excellent documentary about the stupendous failure of a Terry Gilliam film (oddly enough, also starring Johnny Depp).
I highly recommend watching both the features and the film for anyone remotely interested in films and how films are made (and more over...how films are not made).
Final note: after seeing how much Jack Davenport is in the special features, and remembering how kick-ass he was in the film (because Norrington = awesomeness), it really surprises me that he hasn't gotten bigger recognition for the film. (Like...his name in the trailer for the 3rd installment...)
So yes. Whip out those disc twos and prepare for hours and hours of Piratey-movie goodness.