Bob Harper's "Totally Ripped Core" is only about an hour long, but it was enough to make me sore for days and days afterwards.
In other words: I recommend it. :)
Some of the moves included:
-slow-motion one-legged deadlifts
-"killer" plank twists that actually are killer, because on top of your normal plank twist (bringing your knee to your armpit while you hold plank), he has you then drop your hip and stick your leg out straight underneath your suspended torso. Ow . . .
-lots of other body-weighted isometrics
This DVD certainly worked my core, but it also hit the shoulders, and big muscle groups like the quads and hamstrings, so there was never any question about whether or not I was burning a ton of calories.
If you're looking for a challenge that's varied enough that it's fun too, give this one a try.
Peace of Christ to you,