The Tk toolkit provides a Motif-like object set for use typically with tcl,
an interpreted language. See the FAQ list for comp.lang.tcl. The main source
area is sprite.berkeley.edu (128.32.150.27) in pub/tcl. Version 7.5 was
released 5/96 along with version 4.1 of TK; see
ftp://ftp.smli.com/pub/tcl for sources and 
http://www.sunlabs.com/research/tcl for information.

Marx is an interpreted script language  based  on  a  C-like syntax.   It
provides a quick way of creating Graphical User Interfaces in X windows.
Besides GUI  building,  marx also provides simplified schemes for UNIX
process control, direct shell command/script execution and inter-client
communication via sockets.  Version 1.1b1 was released 6/96. See
http://spock.ece.drexel.edu/marx for information.

EZWGL, the EZ widget and graphics library, implements a few Motif like
widgets and a few OpenGL like graphics commands.  EZWGL is released under
terms of the GPL. It can be found at
ftp://ftp.x.org/contrib/widgets/EZWGL.tgz . Information: Maorong Zou
(zou@math.arizona.edu) [8/96]

ParcPlace (Pure Software?) is making freely available its popular
ObjectBuilder and Object Interface (OI) products for the Linux operating
system.  ObjectBuilder is a GUI builder written completely in C++, that
enables UNIX C++ developers to apply the principles of object-orientation to
the development of user interfaces. OI, a C++ class library, provides the
toolkit foundation for ObjectBuilder. OI implements the look-and-feel of both
Motif 1.2 and OPEN LOOK. OI is built directly on top of Xlib and is
unencumbered by runtime royalties to any party.  ObjectBuilder and OI are
very extensible, actively facilitating the use of subclassing to create new,
reusable, user interface components.  Sources are on tsx-11.mit.edu in
/pub/linux/packages/OI and available from ParcPlace (+1 408 481 9090).

Garnet is a Common Lisp-based GUI toolkit. Information is available from
garnet@cs.cmu.edu.