Notes:
CML is Chemical Markup Language. In simple terms it is "HTML for Molecules". First XML DTD (in any domain), launched February 1998.
http://www.xml-cml.org/
MathML is a W3C standard, a low-level specification for describing mathematics as a basis for machine to machine communication. MathML can be used to encode both the presentation of mathematical notation, and mathematical content.
http://www.w3.org/Math/
VoxML is 'The Markup Language for Voice Applications'. Motorola September 1998. The main goal of Motorola's VoxML effort was to offer a common approach and broadly supported platform for voice applications. VoxML technology enables the application interface to be in the form of dialogues: navigation and input is produced via speech recognition of end-user's voice and output is produced via text-to-speech technology or recorded audio samples.
In October 1998 W3C started working on VoiceXML
http://www.w3.org/Voice/
SVG is scalable vector graphics, language for describing two-dimensional vector and mixed vector/raster graphics in XML. Vector superior to raster in most cases due to ability to scale (like postscript) to any resolution. description of geometric objects rather than fixed copy of them.
http://www.w3.org/TR/SVG/
SMIL is Synchronized(sic) multimedia integration language. Enables simple authoring of interactive audiovisual presentations. SMIL is typically used for "rich media"/multimedia presentations which integrate streaming audio and video with images, text or any other media type.
http://www.w3.org/AudioVideo/
XUL (pronounced zuul) is XML-based user interface language. Describes an interface. See mozilla.
http://www.mozilla.org/xpfe/languageSpec.html
Glade is a free user interface builder for GTK+ and GNOME. Interface details stored in XML.
http://glade.gnome.org/