I just wanted to share these great butt workouts I've found on Youtube.
It's by the BeFit channel and is called 30 Day Butt Lift Workout
My progress from just using the elliptical/walking had begun to plateau so I added these workouts. I'm on about day 9 (I repeated one day, too) and have started noticing some difference; my pants aren't as tight. Also, they work the thighs.
I'd definitely suggest adding these before/after your usual cardio workout, or between cardio days.