Well squats and deadlifts should be part of any routine aiming for this ^^Basically I'm looking for exercises to compile a kick ass leg workout program.
you can do those with kettlebells though you'll be doing a lot of reps unless you got the big, heavy and expensive ones.
Additionally and probably more apt for kettlebells specifically are overhead squats
Make this your exercise of choise and you will be a super bad ass.
Just do a Google or Bing image search on Overhead squats. With kettlebells they would be even harder because you have to stabilize your arms independently in addition to your core while keeping balanced.
super bad ass