SpeQ Mathematics - SpeQ is a small, extensive mathematics program with a simple, intuitive interface.
MathType - The Professional version of Equation Editor- MathType is a powerful interactive tool for Windows and Macintosh that lets you create mathematical notation for word processing, web pages, desktop publishing, presentations, and for TeX, LaTeX, and Math…
Qalculate! - Qalculate! is a multiplatform multi-purpose desktop calculator.
Math Magic - MathMagic Equation Editor for Desktop Publishing software & Word Processors, Adobe InDesign, QuarkXPress, MS Word, iWork, for Technical writing with very easy interface and fast input.
NumWorks - The graphing calculator that makes learning math easier.
MathCast - MathCast is an equation editor, an application that allows you to input mathematical equations.