Editors

Glimmer
An all-purpose editor. Features include find/replace, goto line, syntax highlighting, undo/redo, tear away windows, as well as many other standard editor features.
http://glimmer.sourceforge.net

Lyx - The Document Processor
A free program that provides a more modern approach of writing documents with a computer.
http://www.lyx.org/

nano - improved pico editor
nano is a good editor and a replacement from GNU for the pico editor from washington.edu used with pine. Has both search and replace and mouse support.
http://nano-editor.org

NEdit
GUI style plain text editor for X Windows Motif systems, including on MacOS X, OS/2, MS Windows. [Open Source, GPL]
http://www.nedit.org/

QuickHelp - Linux Help Authoring
QuickHelp is a development tool for quickly creating and distributing online help for Linux applications. QuickHelp consists of a QuickHelp Builder for creating help systems and a QuickHelp Viewer for deploying them to end-users.
http://www.excelsoftware.com/quickhelplinux.html

Siag Office
A free office package including word processor, spreadsheet, and graphics animator.
http://siag.nu/

Sourcepole: Hex Editors
Links to hex and binary editors available on the web.
http://sourcepole.com/2006/9/7/hex-editors

The Vile Editor
An editor with the finger feel of vi with many extensions and an optional GUI for Athena, Motif, OpenLook and others.
http://invisible-island.net/vile/vile.html