All the workouts I seen in the BFL book for abs are not resistance-based exercises.  They're either a crunch/twist (upper/oblique) or a leg raise (lower)  - the Journal (and also the workout sheets)  seem to indicate that these should be weight-based, which is what I'd prefer to do.

There's an ab machine at my gym that I've used before, with straps that come over my shoulders in a sitting position (bar above my quads to hold my legs down), where I just crunch up.  I can definitely feel the burn after awhile, but I was wondering if I'd be missing / neglecting parts of my abs.

One of my general frustrations with the book is that I like to work with barbells or machines, and I feel it doesn't offer a lot of options as far as that goes.  I've so far been doing exercises that just target the major muscle groups.  (For now, I've started with machines, until I can get used to the workout a bit more).  I'm not much of a dumbbell / swiss ball kind of guy.  What do you guys do for abs?