Tcl/Tk Extensions and Information Page
Schwartz Computer Consulting Services Tcl/Tk Extensions
http://www.schwartzcomputer.com/tcl-tk/tcl-tk.html

Unicorn XSLT Processor
Unicorn Enterprises SA is a privately-owned Swiss company. It develops computer software, technologies, and solutions. The company is specialized in document management, output management, solutions for private banks, Intranet applications, XML technologies, consulting services.
http://www.unicorn-enterprises.com/products_uxt.html

Firefox Extensions for Web Developers
You will find many Firefox Extensions listed in drx, and they are located in almost as many categories. The goal of this page is to consolidate the best of them into one view in order to demonstrate this diversity. There are hundreds of other fine examples that are not listed here. The ones that are, were selected because they are focused on Web development
http://loadaveragezero.com/drx/extensions

Jeremy's Mozilla Extensions
A useful collection of FREE Mozilla, Firefox and Thunderbird extensions written by Jeremy Gillick
http://mozmonkey.com/

Swindle - Scheme with OOP extensions
A CLOS-like object system for MzScheme. Many other extensions like a generalized set. (a la SRFI-17).
http://www.barzilay.org/Swindle/

Extension Room
Available extensions for Mozilla. Also available are Firefox and Thunderbird extensions.
http://extensionroom.mozdev.org/

Public Domain extensions
Public domain extensions for ESRIS's ArcView GIS 3.x
http://www.disk-world.net/AVDOCS/AV_extensions.htm

ArcView Extensions
ArcView extensions - Avenue scripts - ArcView Utilities
http://www.geosnap.com/Main.htm

Michael's Firefox Extensions
Michael Langley's Firefox Extensions - W3C Page Validator, CSS Validator, RSS Validator, Options Toolbar.
http://www.nu22.com/firefox/

RFC 1522
MIME (Multipurpose Internet Mail Extensions) Part Two: Message Header Extensions for Non-ASCII Text. K. Moore. September 1993.
http://tools.ietf.org/html/rfc1522