Fckeditor

FCKeditor is a lightweight HTML text editor intended for embedding in a wide variety of projects. It takes it's name from it's author, Frederico Caldeira Knabben (FredCK.com). You can find information on using the editor at http://www.fckeditor.net/.

Is it well maintained?

In a word, YES. FCKeditor is used by companies as large as Adobe, to tiny content management systems like vlwcms. There is a lot of interest in future development and security of this tool, which is one of the reasons we chose it as the editor for vlwcms.

Is it expandable?

Yes. There is a built-in system for adding plugins to FCKeditor and vlw adds internal links via this mechanism. If you're interested check out the developer's documentation on www.fckeditor.net.