DataFit
DataFit is a tool used to perform nonlinear regression (curve fitting), statistical analysis and data plotting. What sets DataFit apart from similar curve fitting and regression programs is its ease of use. DataFit is driven by a well-designed graphical interface, so there are no complicated... With DataFit, you can perform linear or nonlinear regression on data containing up to 20 independent variables. ... DataFit also includes forward selection, backward elimination, stepwise selection and manual variable selection modes to help determine which independent variables should be included...
http://www246.pair.com/oakdale/datafit.zip - 6Mb - Download - Screenshot

Auto2Fit
Auto2Fit is a revolution tools and beats all other simliar ones in the area of nonlinear regression! Almost all data analysis software packages (SPSS, SAS, Statistical,Origin Pro, DataFit, Stata or Systat) need end-users to provide/guess initial start values, and the successes of nonlinear... Auto2Fit has turned to be the best one for nonlinear regerssion analysis nowadays. ... Conjugate-Gradient Method (CGM) 11. ... Simulated Annealing (SA) 6. ... Simplex Method (SM) 7. ... Levenberg-Marquardt (LM): standard LM and Global LM 8.
http://www.torry.net/apps/utilities/science/Auto2Fit_Setup3.zip - 0b - Download

NLREG
NLREG performs nonlinear regression and curve fitting. NLREG fits a mathematical function whose form you specify to a set of data values. Virtually any type of function can be fitted. NLREG includes a programming language similar to C that you use for describing the function to be fitted. ... The programming language includes a large selection of built-in library functions (sin, cos, log, exp, etc. ... ) that makes it easy to describe complicated models. ... Two dimensional line and three dimensional surface plots can be generated.
ftp://ftp.nlreg.com/nlrsetup.exe - 1Mb - Download - Screenshot

Data Master 2000
Free software for automation of professional measurement systems, data acquisition, processing and analysis. Especially suitable for scientists who would like to make high-performance, precise measurements in the experimental physics. Optimized for real-time operation, provides OLE-compatible... Features include powerful visual tools (graphic editor, digitizer, base line subtractor), wide set of numeric and symbolic calculations, nonlinear Levenberg-Marquardt regression, and more. ... Distributed with full source code.
http://v10.datamaster2003.com/distrib/dmsetup.zip - 2Mb - Download - Screenshot

DMFitter ActiveX control
DMFitter ActiveX control allows you to add sophisticated regression analysis tools to your software in a few lines of code. Features include: both linear and nonlinear (Levenberg-Marquardt) least squares curve fitting algorithms, arbitrary user models (defined analytically or by string... Examples for Excel, VB, Delphi, MSIE, Data Master 2003 and scripting languages are included.
http://www.datamaster2003.com/downloads/fitter.zip - 198Kb - Download - Screenshot

Data Master 2003
Programmable scientific and technical graphics optimized for automation of test and measurement systems, data acquisition and post-process. Especially suitable for scientists who would like to make high-performance, precise measurements in the experimental research. ... Features include powerful visual tools (graphic editor, plot digitizer, base line subtractor), wide set of numeric and symbolic calculations (integration, differentiation, smoothing, etc), linear and nonlinear NLSF (Levenberg-Marquardt) regression analysis, configurable user interface and more.
http://www.datamaster2003.com/downloads/dm2003.zip - 5Mb - Download - Screenshot

Fornux PowerCalc-GX Student Edition
Compute 60 digits precision calculations, render beautiful 2D/3D graphics and histogram/scatter plot quickly with smart formatting, trace your graphic coordinates and send professional reports in seconds. Enter your data as a vector, mixed/improper fraction, any degree/radian/grad angle,... The program comes with a complete documentation, recognizes expressions having polynomials with implicit multiplications, affects entire expression to any variable upon request (thus programmable), and spaces your operators intelligently.
http://www.fornux.com/calculator/fornux-calculator-se.exe - 2Mb - Download - Screenshot

CurTiPot Acid-Base pH and Titration
CurTiPot is a powerful all-in-one freeware for acid-base equilibria calculations such as pH of aqueous solutions, dissociation degree of weak and polyprotic systems, pKa determinations, simulation of titration curves and analysis of real titration data with chemometric tools like interpolation,... volume of titrant data of simulated and real potentiometric titration curves by two methods: i) graphical representation of curves, assisted by cubic splines interpolation and smoothing of derivative curves for accurate evaluation of inflections (end-points); ii) determination of concentrations...
http://www2.iq.usp.br/docente/gutz/curtipot/curtipot_.zip - 305Kb - Download - Screenshot