MathType

MathType is a powerful, interactive tool that will revolutionise the way you create print and Web-based documents that contain maths. MathType works with any word processor, presentation program, page layout program, HTML-authoring tool and other types of software, to create mathematical notation for research papers, class materials, Web pages, slide presentations, journal articles and books. (Source: http://mathres.kevius.com/software.htm)