Guile (GNU's Ubiquitous Intelligent Language for Extension)
A library implementation of the Scheme language plus various convenient facilities. It's designed so that you can link it into an application or utility to make it extensible.
url: www.gnu.org/software/guile/guile.html
Guile Object Oriented Programming System: GOOPS
Object-oriented extension to Guile; very close in spirit to Common Lisp Object System, CLOS (CLtL2), but adapted for Scheme language; gives full OO system with multiple inheritance, generic functions with multi-method dispatch.
url: www.gnu.org/software/goops/goops.html
guile-gtk
Guile bindings for Gtk+.
url: www.gnu.org/software/guile-gtk/
guile-gtk-general
Maillist for general discussions about the guile-gtk project.
url: mail.gnu.org/mailman/listinfo/guile-gtk-general/