For those of you who are following the calculator debate on Planet KDE, here is some more ideas:

Give the ordinary calculator, with buttons, a results history and a command line, reflecting what you type or click. Then make it possible to type more advanced commands such as `sin`, `cos`, `sqrt`, etc.

In the typing mode, introduce variables. There must be a few such as `mem` for the memory functions M+, M-, MR and MC, and `ans` for the last result.

For the brave user, also introduce a 2D plot with a free variable, such as x. Simply type `plot( formula, from, to )` and you get a second window with the plot. Perhaps a matlab-like behaviour, where one can keep plotting in one window would be useful.