You don't necessarily need to be tall to have a great spike. As long as you can get off the ground is all that matters. It feels great when you get to the point where you get a couple feet off the ground, but it takes a lot of practice to get to this point.
If you get a great kill in a game, it's usually remembered since it only happens once in a while because you aren't that accurate. However, over time and with practice you will always be slamming the ball in the other team's face. To get to this point, you'll probably need some volleyball jump training to help you get more elevated off the floor. Some people prefer just jumping over and over again, but that kind of gets tiring after while.
So, I would rather do something else then just keep jumping up at the net a hundred times. To get higher off the ground, you just need to build up your legs. You can to this by running, squats, doing something with a resistance, wall sits, etc. These things may make your legs hurt at first or make them sore, but it's not as boring than jumping a whole bunch of times. Also, you can find volleyball training aides which help in building up your legs.
Find a volleyball jump training that you like best, but try not to do too much at one time. Also, make sure you through in some basic volleyball drills in practice since it doesn't have to be hardcore the whole time. Also, just for fun you want to work in some creative volleyball drills that the team actually wants to do!
Also see volleyball training aids for more details.