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.
nonlinear regression regression modeling surface fitting

TriLookup 

Excel add-in with eleven powerful worksheet functions for 1, 2 and 3 variable lookup and interpolation (closest-value, linear, piecewise parabolic or hyperbolic, cubic spline) and polynomial curve fitting. Includes online help and example workbooks.
excel add-in spreadsheet lookup interpolation

TriLookup Mac 

Excel add-in with eleven powerful worksheet functions for 1, 2 and 3 variable lookup and interpolation (closest-value, linear, piecewise parabolic or hyperbolic, cubic spline) and polynomial curve fitting. Includes online help and example workbooks.
excel add-in spreadsheet lookup interpolation

vCalc 

vCalc is a keyboard driven scientific calcualtor, that works using the RPN notation common in well known scientific calculators. It supports a complete set of math, binary and statistical operations.
vcalc rpn keyboard scientific statistical calculator

Vector Eye Basic 

Vector Eye is a great raster to vector converter that exports to SVG, Ps and Eps. It recognizes all major raster formats (BMP, JPEG, PNG, TIFF) .Compatible with Adobe, Corel, Jasc, Macromedia, Microsoft and all Svg, Eps, Ps editors.
raster bitmap path vector converter illustrator coreldraw svg svgz ps eps scalable vector graphics bmp gif

Graphit 

Low cost 2D function plotting software. Use up to 8 functions with cascades. Displays 2 simultaneous plots with cursors positions and deltas. File load, save, and print. Input point overlays for curve fitting. Trig, Ln, Log functions supported.
graph plot function plot math graphing software home school curve fit