Gnocl - A gtk+/gnome extension for Tcl, loosely modeled after the way Tcl interfaces with Tk.
A HTML Widget for Tcl/Tk - A loadable shared library widget implemented in C that interprets HTML.
Img - Enhances Tk by adding support for the following image formats: BMP, XBM, XPM, GIF, PNG, JPEG, TIFF and postscript.
[incr Tcl] - Provides extra language support needed to build large Tcl/Tk applications by introducing the notion of objects, which act as building blocks for an application.
[incr Widgets] - An object-oriented mega-widget set which extends Tcl/Tk and is based on [incr Tcl] and [incr Tk].
An Introduction To Pthreads-Tcl - Document describing the changes to Tcl that enable it to be used in conjunction with POSIX Threads (pthreads). A download for Linux is available.
Open Design and Integration Environment (ODIE) - An extension for realtime control and simulation. It adds a realtime task switcher and a tree-structured data base, as well as a matrix expression toolkit.
Scotty - An extension for Tcl which provides access to network management information sources.
Sensus Consulting - Featuring a binding to the LDAP C API, an extension that provides features of OpenSSL, a "pure Tcl" implementation of [Incr Tcl] and [Incr Tk], and a Tcl interpreter that allows any Tcl program to run as a Windows NT Service.
Snack Sound Extension - Adds commands for basic sound handling and primitives for sound visualization.
SSLtcl - A free loadable module for Tcl that extends the socket command with SSL functions. That is, it makes it possible for Tcl applications to communicate securely over the Internet.
Tcl SourceForge Project - A portable extension that provides the power of OpenSSL to Tcl programs. This extension can be used to utilize SSL encryption on top of any valid Tcl Channel - not just sockets!
TCLBridge - Allows Tcl/Tk to be used from any COM/ActiveX container, including VB, .NET, IE, and VBScript.
TclGtk - A project to provide Tcl with access to the Gtk GUI library.
tcllib - A collection of utility modules for Tcl. These modules provide a wide variety of functionality, from implementations of standard data structures to implementations of common networking protocols. [Open source, BSD License]
TclSOAP - The TclSOAP package provides a natural binding from Tcl procedures to SOAP or XML-RPC remote procedures. Both client and server support is provided.
TclXML - Part of a project to make XML available to TCL programs. Two parsers are available: a front end to Expat and a native TCL one.
Tix Widget Set for Tcl and Python - Tk Interface eXtension, a set of user interface components that expand the capabilities of Tcl/Tk and Python applications.