Gedit

Gedit is a text editor for the Gnome desktop, based on GTK+ and gnome libraries.

It is a simple yet powerful editor with the standard features of any text editor combined with powerful features such as plugins to expand the application. A list of plugins available:
 * Spell checker
 * Insert Date/Time
 * Word count
 * ASCII table
 * Diff compares two documents or files
 * "Shell Output" inserts output from a shell command
 * "Tag List" inserts "tags" for many common markup languages (HTML, Latex, etc.)