There is a lot of useful stuff there worth checking out. For example:
This is just one of many ways to increase the difficulty of a basic plank. By taking one arm off the ground and touching the opposite shoulder, you increase the load/stability requirements of the abdominals/obliques. Try not to "rock" too much from side to side when touching the opposite shoulder.
Use a 6-12" box for this exercise. Because you're balancing completely on one leg, more proprioception, balance and stabilization is required (so activation is greater)! Make sure your "off" leg remains completely straight and the "off" ankle remains dorsi-flexed the entire time...just SLIGHTLY touch your heel to the ground. (This ensures that the leg that's on the box is doing ALL the work.)
Or for some conditioning work:
DB goblet squat, DB swings, unilateral curl + press, squat jumps