A body fat calculator that requires just a tape measure.
You measure your height, waist and neck (as a man).
http://fitness.bizcalcs.com/Calculator.asp?Calc=Body-Fat-Nav...
The site is in 90's retro style. You can click on the question mark at the bottom left to see an explanation of all fields.
Someone with BMI of 27 ("overweight") and 16% body fat ("fit") and no belly (but no six-pack either)