I like this article and I do these drills. I know it says for quickness but any kind of repetitive jumping will help your vertical.

http://www.ihoops.com/training-room/strength-and-conditioning/5-Jump-Rope-Drills-to-Improve-Quickness.htm

Also, I like to do wall sits and jump squats. For the wall sits just bend your knees and place your back straight against the wall. Hold this position for as long as you can. For jump squats sit back into a squat and then explosively jump up out of it. As you land go right back into a squat and jump again. There shouldn't be any slow time during the exercise. Just keep going. Make sure you do a good solid warmup before you workout, maybe run in place or do jumping jacks, and then stretch. Also, be sure to stretch afterwards. I hope this helps.

i like to jump rope alot and do a lot of cone drills where u jump back and forth over cones