TeamWave developed a variety of collaboration tools, using Tcl and Tk extensively.
The standalone product, TeamWave Workplace, featured a Tk-based desktop application offering whiteboard, chat, and a variety of other collaborative tools.
The later web based versions didn't require users to download client software. Though Tk was not used for the GUI (it was Java-applet based, again so that no download is required), Tcl and a Tk-like API were used on the server to drive the user interface.
The various products were written in a mix of Tcl and C, and relied on MetaKit for storage. The web versions also used AOLserver.
For more information, contact Mark Roseman.
The company was acquired in late 2000. The original web site [L1 ] has since been shut down, but Mark maintains a retrospective site [L2 ] with some additional links and information.