Free Software for GNOME
gedit
gedit is a free and open source IDE native to the GNOME desktop environment. With gedit you can work with a wide range of programming languages including C, C++, Java, JavaScript, HTML, XML, Python and Perl. The IDE automatically detect programming language and provide code color highlighting accordingly. It also include features like search and replace, spell checking, printing and support for most filte types.
Eye of Gnome
The classic Eye of GNOME is the official and default image viewer for the free and open source desktop environment GNOME. The application comes bundled with GNOME and is in later releases known as Image Viewer. However, Eye of GNOME can be used in any Linux operating system or distribution. It also share many similarities with another official image viewer for GNOME called gThumb
Anjuta
Anjuta is an IDE (integrated development environment) developed for the GNOME Project. With Anjuta developers can work with programming languages like C, C++, Java, JavaScript, Python and Vala. The IDE provides full Glade integration that can be used for WYSIWYG UI development for GTK+/GNOME applications and GDE integration for onboard debugging.