On the front page of a site I'm working on there's a small slideshow. It's not for pictures in particular, any content can go in, and I'm currently setting up the editing interface for the client. I'd like to be able to have one/two/more columns in the editable area, and ideally that would be via CSS - does anyone know of a WYSIWYG editor that supports this? I'm using Drupal (would prefer not to involve Panels as it would require a bit of work to make it a streamlined workflow for content entry) in case that matters to anyone.

To start the ball rolling, one way would be to use templates. I know CKEditor supports templates, and it looks like TinyMCE might have something similar. I don't know how well these work with tableless columns (the CKEditor homepage demo uses tables to achieve its two column effect).

Holding out for a cool solution!