MathType 5
Published by: MathType. A free demo version is available.
MathType™ is a powerful interactive tool for Windows and Macintosh that lets you create mathematical notation for word processing and desktop publishing documents, web pages, presentations, and for TeX & LaTeX and MathML documents. MathType is the fully featured version of the Equation Editor that is included in Microsoft Word, Corel WordPerfect, AppleWorks and many other products. MathType has been used extensively on MathsNet.net particularly in the AS/A2 resources. Some examples: