I found all sorts of mortgage and car loan calculators but none of them was a Patch on Andrew's loan calculator.
What's more, because I'm hopeless at the kind of calculations involved, Andrew created the calculator for me.
I've been working with websites for more than ten years and I have never come across such good support - even from paid extensions.
If you need a customised calculator it has to be Calculator Generator - and if you're not clever enough to work out the maths yourself it seems Andrew is happy to help.
He earned every penny of the small donation we made.