Mm, a variety of opinions ... My regular ab routine for several months now has been 4 sets of 15 to 30 reps, usually 2 sets of regular, incline or swiss ball crunches, and two sets of incline hip raises, bench V tucks or swiss ball knee tucks. I used to sometimes throw in obliques, but I never felt like I could feel anything, really - anyway not the burn you get with incline crunches.
This routine has worked wonders - before, I only worked abs twice a week, now it's this routine 4x per week. You can't see them (well, blurry outlines slowly coming through), but boy can I feel those blocks under there - much stronger and more defined.
I was just wondering if, for variety, and possibly a slimming effect, I shouldn't do sidebends. I tried them the other night and am still a little sore there now.
Just for the record Phem, I also do squats and deadlifts (well, stiff-legged dl's) without a belt.
And b fold, "Remember...you are not going to grow huge obliques over night": ha ha, point taken - don't we all wish for huge growth overnight!