If you do a lot of small calculations using your phone, Calcium can make you do it faster. This is not meant to be an advanced calculator, but to be an easier to use calculator. You will need less keypress compared with the standard calculator for doing most calculation. The standard calculator has more features such as scrolling, and percentage calculation.
Calcium was developed by Trent Fitzgibbon and Michael Ahokas, and you can download it fom http://mtvid.com.