a free source code editor which supports several programming languages running under the MS Windows environment. based on Scintilla edit component (a very powerful editor component)
a free user interface builder for GTK+ and GNOME interfaces designed are saved as XML, and by using the libglade library these can be loaded by applications dynamically as needed. (Glade can also generate C code)
a pure Java implementation of the Ruby interpreter is tightly integrated with Java to allow both to script any Java class and to embed the interpreter into any Java application.