RORO01  Doesn't work on iMac Intel 10.4.11. The developer states in his website that it should work on other OSX systems apart from Leopard.  
(Version 2.5)

DAN  Wingsy's problem with 3^0.5 is not the fault of the developer of Longhand, but of the underlying calc executable, which does not compute fractional powers (at least in the above form) or with normal build options for the package. As for the other issues: I don't care.

calc is a very powerful (open source) extended precision math system. I did not have to do anything special to compile it on my machine using the compilers supplied with Developer Tools Xcode v. 1.2

The procedure for piping inputs to calc and piping its outputs back into a text view, while not completely trivial, is the work of an afternoon, especially if you have some Cocoa sample code to work with. The real work was done by the developers of calc, and although the author does credit them in appropriate places, he could do more to declare that fact in the info he has supplied here at MU.  
(Version 2.3)

WINGSY  This version STILL produces an error for equations such as: 3^.5

Also, when triggered to calculate with the Enter key, the cursor is left between the equation and the result. From there, I don't see how to get to the next line without grabbing the mouse and positioning the cursor at the end of the line before I hit Return to give me a new line. If there is some other way it sure isn't very intuitive to me.

I almost had this app in my dock, until I discovered the issues (to me anyway) above... and then I stumbled onto Chipmonk Basic. I gave this new version another try but it still looks the same to me.  
(Version 2.2.1)

ANONYMOUS  This is cool, but it really need to be made into a service too, so you can use it in any application.

Yes, I know there's CalcService, but this does a lot more..  
(Version 2.2)

ANONYMOUS  Not really a new idea. MathPad has been around for years. It includes plotting and is also free.  
(Version 2.1)

APIKORUS  Outstanding! Fancy calculator simulators more often than not miss this crucial point: the most important feature is ease of use. Noone wants to hunt and peck with the mouse to press one or more buttons to get an inverse hyperbolic tangent -- anyone can type "atanh" much faster. Longhand is perfect -- a beautifully designed and conceived piece of software. I can't believe it's free.  
(Version 2.1)

ANONYMOUS  Exactly, what I have been waiting for! Thanks!  
(Version 2.1)

ANONYMOUS  Sort of a GUI version of the old UNIX standard "bc"?  
(Version 2.0.1)