Great Calculator
This is definitely the best calculator I use, on the iPhone or elsewhere. I actually pull out pCalc more often than I do my shiny HP-35s. With the latest update, it opens much faster than in the past (even on an iPhone 3G). There are plenty of settings, so even the most picky calculator user ought to be able to set it up just as they like. Well done, Mr. Thomson.
Roguelazer about
PCalc, v3.5.3