Bob, I use a tuner (Cleartune on my iPhone) for tuning my drums. It helps me immensely with fine tuning the drums, consistently tuning and retuning my drums, and checking tuning intervals between heads or drums. I can precisely tune to whatever pitch I wish, as well as retune back to that exact tuning a day or a month later.
There is a huge knack to using the tuner, though. When a drum is way out of tune, the tuner just doesn't give a useful reading, as it can't sort out all the tones and overtones. I've found I get the best luck making sure that all the oposite pairs of lugs are tuned to each other. By that, I mean that a given lug is aproximately in tune with the lug directly across the head. That minimizes the wierd overtones and let's the tuner get a reading.
You also need to experiment with where you strike the head (closer or farther from the rim), how hard you strike, where you hold the tuner (usually right above the head, but sometimes it works better holding the tuner close to a lug, below the rim), and how close you hold the tuner to the drum.
I'm sure some people will say something like, if you've already mostly tuned the drum by hand, why not just finish by hand. Personally, I have a lousy ear for pitch, so getting whatever help I can at any step in the process makes my life easier.
So a tuner doesn't perform miracles, and won't tune a drum for you. But it can be a valuable tool and help with the process.