MACalc is a native RPN/Algebraic calculator for iPhone.

Changes:

0.1.6 – the “tap area” to move from Integer <> Float is now restricted to the “display area only”
skins can now be added to “/var/root/Library/MACalc/Skins” (“/var/mobile/Library/MACalc/Skins” with FW 1.1.3)
fixed “decimal point” display in Settings

http://web.newsguy.com/marcio/iphone/macalc/