There used to be a photographer on here that recommended a range between 1/2FL to 1/5FL.
If i'm shooting in the theatre at actors, i try to use a min of 1/160s, but that often still give me blur on hands and arms.
I have a friend who must be math challenged or she would not recalculate for different zoom FL. She was having a lot of blurred pictures and blamed it on the camera. So in some frustration, i told her to just use 1/500s. So about 2 weeks later, after i forgot about my advice, she thanked me for the tip and how much sharper her pictures are - she uses a D7000. So the lesson here is: if you are out of doors and have plenty of light, use 1/500s, you'd be amazed at how good that looks
Reminds me, i was out on a whale watching boat with some sizable chop on the water. The boat was moving like crazy. So i bumped up the shutter speed to 1/2000 and didn't have much hope. But the pics came out great.
Its funny how our cameras are so programmed to give us the minimum shutter speed all the time.