I hate the treadmill but for those who don't: TREADMILL SHREDMILL WORKOUT! It's 45 min long with a 5 min cooldown. This is part of my bikini comp cardio. And yes, you CAN last this long on a treadmill. Trust me.
Ballet Abs - I don't remember doing any of these separately (except for crunches) when I use to dance. I got my "ballet abs" by holding it in during class for 10 years; however, these exercises are great for anyone.