Vi was one of the original editors, and while difficult to use, loads much faster than, for example, Emacs, and is good for making small changes to files. http://www.vim.org/
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
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
CodeCommander is a 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://CodeCommander.sourceforge.net/