If you use the scale heights of the figures, you have a yardstick..
1/32= is One inch equals 32 inches
1/35= One inch equals 35 inches
1/48= one inch equals 48 inches
etc, etc...
So, a 1/35th scale figure that is one inch in height represents a person 5 feet,10 inches tall, a 1/72 figure is 6 feet tall, etc, etc... (Just don't count those Tamiya 1/48th infantry sets as 1/48... If they're to be believed, all American GIs are 5 feet tall...)
Anyhow, here's a scale calculator
http://www.wwmodelclub.org/extra/sd_scalecalc2.htm
Here's the Google page I started looking on:
http://www.google.com/search?hl=en&q=Model+scale+dimensions+charts&btnG=Search