PyGTK
- Python Bindings for the GTK+ Widget Set
- http://www.pygtk.org/

VDKBuilder
- A Rapid Application Development tool based on VDK, the Visual Development Kit, a C++ wrapper to GTK+.
- http://home.planet.nl/~groe2579/vdkbuilder/

Gtk2Hs
- A GUI library for Haskell based on Gtk+. [Open source, LGPL]
- http://haskell.org/gtk2hs/

guile-gtk
- Guile bindings for Gtk+.
- http://www.gnu.org/software/guile-gtk/

TkLua
- A binding Tk to Lua. [Freeware]
- http://www.tecgraf.puc-rio.br/~celes/tklua/

Ruby/GTK+
- Official GTK+ extension library for Ruby.
- http://ruby-gnome.sourceforge.net/

GtkAda
- Ada GTK+ toolkit
- http://libre.act-europe.fr/GtkAda/

Java-Gnome
- Java GTK+ and Gnome bindings using JNI.
- http://java-gnome.sourceforge.net/

mGTK
- SML (Standard ML) bindings for GTK+
- http://mgtk.sourceforge.net/

TclGtk
- A project to provide Tcl with access to the Gtk GUI library
- http://tcl-gtk.sourceforge.net/

GTK+ for Free Pascal
- Official FreePascal GTK+ translation
- http://www.freepascal.org/packages/gtk.html

MlGtk
- An interface between Ocaml (a dialect of ML) and the Gtk+ toolkit
- http://cristal.inria.fr/~cuoq/mlgtk.html

PHP-GTK
- PHP bindings for GTK+
- http://gtk.php.net/

LablGTK
- Another Ocaml Gtk+ interface
- http://wwwfun.kurims.kyoto-u.ac.jp/soft/olabl/lablgtk.html

m3gtk
- A Modula-3 binding to the Gtk+ toolkit
- http://www.scatcat.demon.co.uk/m3gtk/

Inti
- Integrated C++ Foundation Libraries, including Inti::GTK, a C++ GTK+ binding.
- http://sources.redhat.com/inti/

GTK--
- C++ interfaces and bindings for GTK+
- http://gtkmm.sourceforge.net/

Gtk+Haskell
- Bindings for GTK+ for the functional programming language Haskell.
- http://www.cse.unsw.edu.au/~chak/haskell/gtk/

rep-gtk
- GTK+ bindings for Librep Lisp
- http://rep-gtk.sourceforge.net/