Core exercises?

I had found a core exercise regimen on the site that I wanted to try and now I can't find it.  I see a lot of core workouts with lots of various sit-ups.  This one had lunges, roman chair and side lunges (among others) mixed in with different ab work.  The program was broken down into 6 or 7 workouts that were mixed on different days.  I also remember seeing demonstration stills that showed technique.  Can anyone help me find this program?  Thanks in advance.