I am not 'JS or 'Ajax' developer myself but I just spotted the 'JCE Utilities Mambot' jQuery integration of WYSWYG editor. I thought I should post here.
Since Drupal jQuery is in the core Drupal5, to integrate a 'simple' jQuery WYSWYG editor ~alternative to TinyMCE and HTMLarea (which reqires a 3rd party code) would be possible idea i presume.
'JCE Layout Manager'
http://www.cellardoor.za.net/
some screenshots
image browser and attachment
http://www.cellardoor.za.net/images/stories/sort.jpg
http://www.cellardoor.za.net/images/stories/window2.jpg
JCE Joomla Content editor is overkill like the Joomla itself -imo- But I a WYSWYG editor with basic HTML tag marking + image/media/file browser&attachment functionality would greatly help to improve Drupal on that front.
Also it might help to Drupal 'collaborative editor' effords
What i mean by basic HTML tag marking is an WYSWYG interface to
Drupal default allowed HTML tags: h1, h2, h3, h4, h5, h6, em, strong, code, del, blockquote, q, sub, p, br, pre, ul, ol, li, dl, dt, dd, a, b, u, i, sup,img, table, tbody,td, th, tr,
or/and similar functionality setings of 'TinyMCE Basic view' like in this picture
http://www.midgard-project.org/documentation/tinymce-content-editor/

Comments
I've also spotted JCE and
I've also spotted JCE and think we should ship something simular w/Drupal.
WYSIWYG + img mgr + file mgr = tinymcpuk
What you need is this:
http://p4a.sourceforge.net/tinymcpuk
It works with the Drupal tinymce module.
This is the answer to me!
Webdevelopment | Webbased Applications | Open Source
not quite
the announcement on that page says that they switch away from jquery to mootools.