RPNCalc is a reverse polish notation scientific calculator.
SNAC's a Neat Algebraic Calculator: a desktop calculator that supports simple numeric algebraic calculations
TI-89 Transfer Utility
TI-89 Transfer Utility transfers files onto the TI-89 calculator.
TiLP is a TI calculators - PC communication program using a GTK interface.
tkalc is a pocket calculator for developers and IP network operators. Abritrary arithmetic or logical expressions can be entered very quickly in a text entry field.
Virtual TI emulates nearly the entire line of Texas Instruments graphing calculators, and offers features that speed up both debugging and testing of calculator programs. Windows version is quite stable but the Linux version is only in planning.
Wcalc is a very capable calculator. It has standard functions (sin, asin, and sinh for example, in either radians or degrees), many pre-defined constants (pi, e, c, etc.), support for using variables, "active" variables, a command history, hex/octal/binary input and output, unit conversions, embedded comments, and an expandable expression entry field.
wcalc-applet is a simple calculator applet for the GNOME2 panel using PyGTK.
wmcalc is a small calculator meant for the WindowMaker dock or Afterstep Wharf. It is a simple calculator with basic functions and memory slots, and can launch any external application for more complex calculations.
X-Bc is a graphical user interface to bc. It's big advantage: input and output stay visible at all time for correction and comparation.
Supports base conversions, scientific constants, number theory functions and more.
xfer9860 connects to a Casio fx-9860G graphing calculator and transfers files.
XRPN is a RPN calculator for real and complex numbers with a motif/X11 GUI.