Hi, I use www.linear-software.com for my measurement based body fat. It 'feels' right, I haven't got anything to compare it with, like a body fat scale.
It takes into account height and also build to some extend, since it includes neck measurements.
I'm currently 23.5% bf, which is in the 'normal' range and certainly now, I look 'normal' not fat. I'm aiming at 20% which is the bottom end of the normal range - I can still 'pinch an inch or more' and I'd like some of that subcutaneous fat to go still, so my bra etc. doesn't bite in. So what I'm saying I suppose, is that the measures it gives for me seem to fit with what else I know about body fat levels.
Be interesting to see what you thought of it compared to that site you have been using. I'll go and look at that one!