devot:eeDevoted to ExpressionEngine

One advantage of FCKeditor over TinyMCE is its ability to set editor options on a per-instance basis. That means you can have multiple FCKeditor fields in a publish form, all with different configurations.
This extension enables this flexibility. You can select exactly which textareas you want to convert to WYSIWYG fields, and individually configure those fields. For example, one might be a big WYSIWYG field for body text with a full-featured editing toolbar; another a narrow field for a sidebar with custom CSS file for accurate preview, and a third an “image” field with a simple toolbar that only   allows images to be uploaded to it.

So how does it work?

Each “Textarea” type field’s configuration directives are stored in the textarea that contains the options for “Drop-down List” type fields. Recent versions of EE require you to change the field-type to “Drop-down List” temporarily to see and edit these options.

Setting the first line in this field to the string “wysiwyg” activates the extension, and transforms the textarea into an FCKeditor field with default configuration. Subsequent lines can contain relevant configuration parameters.