ScratchCalc is a calculator implemented using client side technologies (coffeescript and SASS).
It allows for a mix of text and numeric operations, and references to other lines.
So for instance, the following operations are valid
x = 2 // 2
(3)* 2 + 5 // 31
line2 + 2 // 33
x + 5 // 7
3 apples + 2 oranges // 5
Check out a live demo at benmccormick.org/scratchcalc