We all have our favorite developers — one of mine is James Thomson, maker of DragThing, PCalc and PCalc for iPhone. Thomson recently released PCalc 1.9, which is available in the App Store now. One of the new features introduced with this version is in-app purchases, which has been integrated into PCalc Lite.

By integrating the PCalc Store into the app, Thomson gives users an easy way to upgrade and add new features to the app. For instance, if you want to add on conversions to the app, just go to the settings page and buy the Conversion Pack. For $0.99, it will be instantly unlocked and ready for use.

You can also upgrade the free version to the full version using in-app purchasing. The price of doing it this way equals the price of buying the full version, which is available for $9.99.

PCalc [iTunes Link] and PCalc Lite [iTunes Link] are available from the App Store.