Sheet Lightning is a specialised engineering 2D/3D CAD System for creating and unfolding sheet metal designs for fabrication or manufacture. It handles everything from simple cylinders, cones, rectangular ducts and ovals, to adapters, adapting any of these section types, interections and multi-intersections between of any of these types to any level of complexity.

BeamBoy
BeamBoy is a free engineering utility for calculating stress and deflection of structural beams under load. May also be used for shafts. BeamBoy is menu-driven and intuitive.

Orifice
Orifice calculates size, flowrate or pressure drops for gas and liquid orifice meters based on ANSI/API-2530-1991, Part 3 (AGA-3) or the International Standard ISO-5167-1:1991. Customary or SI units.

AlcoDens
Convert density of ethanol-water mixtures to and from concentration expressed in Mass, Volume or Molar terms. Covers concentrations from 0% to 100% and temperatures from 10C to 100C. Calculate blending ratios based on source or blend properties.

CopanMobile for PocketPC
CopanMobile for PocketPC allows you to COGO (coordinate geometry), process field surveys, adjust map traverses, perform map/deed checks, calc curves and areas/perimeters, transform coords, interface with GPS, and import/export Ascii files. It's free.

DataFit
DataFit is a tool for performing curve fitting, statistical analysis & data plotting. Fit equations with up to 100 parameters to data with up to 20 independent variables. Define your own equations or choose from over 600 pre-defined equations.