If you one have one family in your tree then there are ways to do this. PAF will allow you to select people who are unrelated to the main person in your tree. Then you can print a list of just those people.
Roots Magic, not sure about the free version, has a 'Count Trees' option that will count the number of trees in your file and says how many people are in that tree. Not sure if you can print who are in those trees easily though.
I've always wondered why FTM doesn't have the ability to do this. You would think that this a problem and I've seen people ask about it before.