To get Text from a single element you can use getText() method. Please see here: http://docs.cksource.com/ckeditor_api/symbols/CKEDITOR.dom.element.html#getText
If you are talking about getting text from whole page than I think we could create a plug-in that moves down the DOM tree gets text from elements and returns nice plain line of text.
On the other hand I’m not sure if this road is not to slippery. Someone might say that plain line is ok, someone else that ok this is plain text but headers should be in one line a the rest of the text that follows in the other. Someone else might say that when one text ends with a space and the other text begins with it, one of spaces should be removed, someone else might say that they should be felt untouched. Someone might say that some tags should be omitted… and so on.
Perhaps the best solution is to leave this to the user to create a simple plug-in/function which moves down the DOM tree, gets the text from elements and returns it in the form that he/she wants?
