DreamCalc Scientific Calculator
DreamCalc is the smarter alternative to a hand-held Scientific 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. Select from Reverse Polish Notation or two styles of algebraic input,... DreamCalc also offers you a full range of scientific functions, statistics, complex numbers, base-n logic, unit conversions, built-in constants and a powerful polynomial solver. ... It is a "must" for business, science, engineering and education.
http://www.dreamcalc.com/downloads/dc3s_setup.exe - 3Mb - Download - Screenshot

ESBCalc - Freeware Calculator
ESBCalc is a Freeware Windows Scientific Calculator with Infix Notation, Brackets, Scientific Functions, Memory, Optional Paper Trail, Result History List, Customisation of the Colours and Fonts used, Customisation of the Hints, and more. Functions include Trigonometric, Hyperbolic, Logarithmic... 3 log which is the default behaviour. ... Looks best with Windows XP in 800x600 (or better) and 32-bit colour. ... 3 rather than as 1. ... 3) can be entered as log 1. ... Now includes Prefix Function support so that Log (1.
http://www.esbconsult.com/esbcalc.zip - 803Kb - Download - Screenshot

ESBCalc Pro - Scientific Calculator
ESBCalc Pro is an Enhanced Windows Scientific Calculator with Infix Processing, Exponential Notation, Brackets, Scientific Functions, Memory, Optional Paper Trail, Printing, Result History List, Integrated Help and more. Functions include Trigonometric, Hyperbolic, Logarithmic - Base 10, Base... The calculator can have "Prefix Functions" turned on so that when calculating log (25), you can enter log 25 rather than the traditional 25 log. ... The Calculator also has an expression editor that allows the data that has been entered can be then edited and recalculated.
http://www.esbconsult.com/esbcalcpro.zip - 1Mb - 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

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

RPN Engineering Calculator
This RPN calculator offers 250 solutions with six unique keypads. It has a complete help system with individual tips for all but the most ordinary functions and a Tip of the Day feature for new users. You can select fixed, scientific or engineering notation and degrees, radians, or grads as... Briefly, unique to the 6 keypads are: Standard; contains several of the functions found on a normal scientific calculator (log, ln, N! ... ), and some unique to itself: a simple math teaching aid for kids, Wind Chill calculator, and more.
http://www.j-a-associates.com/DnLoads/rpn.zip - 1Mb - Download - Screenshot

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. * Keyboard driven user interface * Four basic operations on integer and floating point numbers...
http://www.icegiant.com/downloads/vcalc.exe - 804Kb - 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,... Expressions are entered in the customary algebraic notation, and only then evaluated. ... Most importantly, advanced features don't obstruct the basic ones. ... You can use as much of Kalkulator's capabilities as you need, without being hampered by the program capabilities you do not need.
http://www.wrotniak.net/works/kalkulator/_zip/kalkulator-inst.exe - 956Kb - Download - Screenshot

Calcute
Calcute is a Free and Compact yet Capable Tape Calculator. More advanced than standard calculators, it is actually an expression evaluator that lets you process arbitrarily complex numeric expressions like: -ln(1+2) * 3% + sin(4 5/6)^7. As shown in this example, you can even enter an exact... You can swap the use of the period and comma in order to use international numeric notation. ... Many scientific functions are supported: logarithms and exponents, trigonometric and hyperbolic functions, normal and inverse.
http://calcute.com/calcute_setup.exe - 137Kb - Download - Screenshot

CalculatorX
CalculatorX is an enhanced expression calculator. It can evaluate an expression for one time. You can use Arithmetic, Logic, Bitwise and Relation operations in your expression. And many system constants and built-in functions can also be used in the expression. ... CalculatorX is powerful, but it is very easy to use. ... You can use it as any calculators you have used. ... Make Work Easy and High Efficiency by using CalculatorX. ... - Alias for operators and functions, eg. ... Here is just a short list of CalculatorX's major features: - Arithmetic operation - Logic and Bitwise operation...
http://www.xoyosoft.com/cx/download/CalcX.zip - 1Mb - Download - Screenshot