Paused squats of any kind are great for building strength in your core, along with other stabilizing muscles. Use a stopwatch for consistency and to really force a good pause.
Chains or bands are often used to help build strength to blow past your sticking points. As you stand in the squat, more weight is added as the chains come up off the floor (more tension is added with bands). Combining pauses with chains kicks everything up a level. Give it a try.