Typesetting

Abacus Math Writer
A java stand-alone program that allows producing equations by transferring onscreen writing to an image. Includes illustrations and sample download.
http://www.jpowered.com/mathwriter/

aMath96
MS-Word template for quickly entering formulas without resorting to the equation editor. Uses standard characters.
http://www.amath.net/english/

Applied Symbols
This company specializes in OpenType fonts for technical and mathematical publications.
http://www.appliedsymbols.com

ASCIIMathML
JavaScript that dynamically converts calculator-style ASCII notation (and many LaTeX formulas) to MathML. Includes free download and sample usage.
http://www.chapman.edu/~jipsen/asciimath.html

Editors and Typesetting
A collection of links to mathematical editors and typestting systems from the Math Forum.
http://mathforum.org/library/resource_types/typesetting/

GIF Images for Math Symbols
A public-domain collection of over a thousand bit-mapped, 12-point, transparent GIFs of mathematical letters and symbols, suitable for display on a web page.
http://us.metamath.org/symbols/symbols.html

KFormula
A formula editor in the KOffice suite, distributed under GPL.
http://www.koffice.org/kformula/

Math Typesetting for the Internet
Complete guide for including math notation in web pages and e-mail messages. Includes links to necessary software and tools.
http://mathforum.org/typesetting/

MathCast
A open source equation editor, with a graphical interface, equation list management, and MathML 2.0 support. Includes feature list, examples, developer information, and downloads.
http://mathcast.sourceforge.net/

MathEdit
Windows program to place typeset-quality mathematical equations into documents. Many features are available via keyboard shortcuts, making math typing faster by reducing mouse movements.
http://www.ktalk.com/mathedit.html

MathML Central
A Wolfram Web Resource for MathML tools.
http://www.mathmlcentral.com/

MathML Equation Editor
Announcing soft4science MathEditor, a graphical MathML equation editor.
http://www.soft4science.de/

MathType
Powerful mathematical typesetting program for word processing and desktop publishing documents. Professional edition of the Equation Editor package bundled with Microsoft Word, Corel WordPerfect, and Appleworks.
http://www.mathtype.com/

meditor
A text editor with some symbolic computation capabilities. Free under GPL.
http://jscl-meditor.sourceforge.net/

PLML: Pattern Language Markup Language
Summary of CHI2003 workshop that covered HCI patterns, including PLML. Page includes summary of the event, program background, and an introduction to PLMLx.
http://www.cs.kent.ac.uk/people/staff/saf/patterns/plml.html

Publicon
A full-featured publishing system for the creation of professional-quality technical documents.
http://www.wolfram.com/products/publicon/

Rapid-Pi
An equation editor for Microsoft Word. Text-based input method is used to enter mathematical formulas, equations and expressions into documents. Page includes screen shots, trial version and FAQ.
http://www.rapid-pi.com

Scientific Letter. Mailer with equation editor
Scientific Letter is an original mail program that allows you to create messages including complex equations.
http://www.sciletter.com/

SciWriter
An XML based WYSIWYG word processor for mathematics and text. The native document format is a subset of XHTML 1.1 and MathML 2.0 Presentation Markup.
http://www.soft4science.com/

Swift
An equation editor in Java.
http://www.geocities.com/SiliconValley/Heights/5445/swift.html