Math Mechanixs
Math Mechanixs is an easy to use general purpose FREE math software program. (FREE registration is required after 60 days). The typical tool for obtaining answers to a mathematical problem has been the calculator. Unfortunately, a calculator can be very limiting. ... The function library is also extendable by the user and is even more powerful when combined with our unique function solver, which provides a quick and easy way to solve any function. ... Until the graphing calculator, the user could not graph their data either.
http://www.mathmechanixs.com/download/mathmech10021.exe - 6Mb - Download - Screenshot

MadCalc
MadCalc is a full featured graphing calculator application for your PC running Windows. With MadCalc you can graph rectangular, parametric, and polar equations. Plot multiple equations at once. Change the colors of graphs and the background. Use the immediate window feature to evaluate complex... Students can use it instead of that tiny calculator screen while you are doing your calculus homework. ... MadCalc provides all the essential graphing functionality without the complexity, cost, or overhead of something like Mathematica or MatLab.
http://www.madlogic.com/download/MC_INST.EXE - 387Kb - Download - Screenshot

DreamCalc Graphing Calculator
DreamCalc is the smarter alternative to a hand-held Graphing Calculator for your PC or laptop! You'll get the intuitive feel and productivity of using a professional hand-held, but one which adapts to your way of working. With DreamCalc, you'll be able to graph functions and plot list data more... Select from Reverse Polish Notation or two styles of algebraic input, and with the optional ability to run in your Windows system tray--DreamCalc will always be there whenever you need to reach for a calculator.
http://www.dreamcalc.com/downloads/dc3g_setup.exe - 3Mb - Download - Screenshot

Advanced Grapher
Powerful but easy-to-use graphing, curve fitting and calculating software. Graphs Cartesian (Y(x) and X(y)), polar and parametric functions, graphs of tables, equations (implicit functions), inequalities and slope fields. Up to 100 graphs in one window. ... Calculus features: regression analysis, obtaining zeroes and extrema of functions, intersections, derivatives, equations of tangents and normals, numerical integration, value tables, calculator. ... The program has printing capabilities, multi-document interface, customizable toolbars.
http://www.alentum.net/files/agrapher.zip - 1Mb - Download - Screenshot

ZGrapher
This graphing calculator can plot y(x), x(y), polar, parametric and table-defined functions. All your graphs and coordinate space may be fully customized. You can comment your graphs using labels and legend. For a few seconds you can obtain derivatives, tangents, normals and calculate integrals. ... Results of your work may be exported to Word or saved as BMP, GIF and PCX pictures. ... Regression analysis will help you to find trend of your data.
http://www.zgrapher.com/zgrapher.zip - 621Kb - Download - Screenshot

DreamCalc Financial Calculator (Pro)
DreamCalc Professional is the smarter alternative to a hand-held Financial Calculator for your PC or laptop! You'll get the intuitive feel and productivity of using a professional hand-held, but one which adapts to your way of working. With DreamCalc, you'll be able to graph functions and plot... Select from Reverse Polish Notation or two styles of algebraic input, and with the optional ability to run in your Windows system tray--DreamCalc will always be there whenever you need to reach for a calculator.
http://www.dreamcalc.com/downloads/dc3p_setup.exe - 3Mb - Download - Screenshot

MathCalc
MathCalc run with the calculator and graph plotter mode. Within the calculator mode, you can compute mathematical expressions, trigonometric, hyperbolic or logarithmic functions. The entered expressions and functions are saved into formula lists. The program has a handy, easy-to-use formula... MathCalc supports adjusting of all chart elements in the real time mode (WYSIWYG - What You See Is What You Get). ... In addition, it is possible to export the graph points to a text file. ... The program allows zooming and scrolling graphs.
http://www.ypssoft.com/program/matce2_1.zip - 1Mb - Download - Screenshot

3D Grapher
3D Grapher is a feature-rich yet easy-to-use graph plotting and data visualization software suitable for students, engineers and everybody who needs to work with 2D and 3D graphs. 3D Grapher is small, fast, flexible, and reliable. It offers much of the functionality of heavyweight data analysis... Other program features include: 1) Built-in expression calculator 2) Mouse cursor coordinate tracking 3) Fully customizable user-friendly interface for highly efficient workflow 4) Ability to import and export data in several popular file formats 5) Ability to copy the graphs and paste them...
http://www.romanlab.com/3dg/3dg.zip - 836Kb - Download - Screenshot

Kalkulator
The Mother of all Calculators, a Swiss Army knife for scientists and engineers. Perhaps the most capable scientific/engineering calculator for Windows. On one hand, this is a calculator: evaluates expressions with more than 100 functions (trig/inverse, log/exp, statisical distributions, Euler,... Hard-to-find features: systems of non-linear and differential (ODE) equations, multi-argument function extremum search and point or histogram fitting with an arbitrary function. ... There ara also unit conversions, physical constants, computer math (binary, octal, hex), and function graphs included.
http://www.wrotniak.net/works/kalkulator/_zip/kalkulator-inst.exe - 956Kb - Download - Screenshot

CplxCalPro
CplxCalPro, CCP, is the most powerful programmable graphicalcalculator for the palm platform. While this calculator is not necessarily designed just to balance your checkbook, you could easily do so. CplxCalPro allows you to perform the most advanced calculations and function graphing without... After developing and testing your programs on the PC or MAC you can save the programs and hotsync them to your handheld. ... Use the Emulator to write your programs for CplxCalPro on a PC or MAC. ... The user manual explains how to do this.
http://www.adacs.com/UserPrograms/CplxCalPro/CplxCalPro.zip - 231Kb - Download - Screenshot