Skips and Bounds for power or speed. 5-5-5 Squats. Multiple Jumps and Hops, I like hopskotch and continous triple jump(except skip to it). Also sets of 100m bounds, followed by 100m strides. Step ups for 3 minutes and 2 minute med ball toss and chase. Lots of good ones, but use your imagination.
Also, I like to add some mini hurdles at various spaces between 100-200 and 500-600 on 600m runs at the end of preseason conditioning or early season. If done right there will be no stutter steps. Just want them to get used to having a good knee lift when tired. You have to be in good shape to do this one.