Warner has gotten into the act, too. On top of great additional clips, Batman: The Dark Knight provides user-generated picture-in-picture video commentaries. Just fire up your Webcam, and upload your two cents--and your impressive Bat-knowledge--to share with the world. The community screening feature lets you sync up with your buddies over the Net to watch a flick in tandem. The feature worked great recently for fans of the film who got to watch it with, and ask questions of, director Christopher Nolan (who apparently had to adjourn to the men's room twice during the chat).

Will any of this persuade people to sprint out to the store and buy a Blu-ray player? Probably not, but it might make connected-deck owners feel better about their purchase. (We'd like the ability to re-edit movies the way we see fit and finally make Star Wars: Episode One watchable.) In the meantime, other films offer interesting extras--even if you aren't interested in the film itself.

Some flicks, such as the video-game-inspired Max Payne, incorporate control code. That's terrific if you happen to own a pricey piece of furniture with hydraulics programmed to lift and lower when synced with a player. Max Payne, along with a couple other recent titles such as Babylon A.D. and Wanted, also experiments with digital graphic novels embedded on the disc.

Many Blu-ray Disc movies offer all sorts of picture-in-picture bonus content. This capability, called Blu-ray Bonus View, is accessible on any player labeled as Blu-ray Profile 1.1 or Bonus View capable (Profile 2.0 models, commonly referred to as BD-Live players, can also handle Bonus View content).

The Bonus View content lets you get behind-the-scenes commentary and special effects breakdowns in a window. But some films offer a deeper look inside a movie's world. In Doomsday, for example, pop-up windows give you greater context, explaining factions and weapons as the movie unfolds. The technothriller Vantage Point combines the perspectives of all the characters in the film and follows their locations with an in-film heads-up display while you watch everything unfold.