I've used EmbeddedWB from bsalsa. Basically it is the same as Delphi's TWebBrowser, but you have access to more features of the IE automation object. In the browser I loaded an HTML which looks like:
Edit description
Marking an element by IE specific attribute "contenteditable", the IE implementation let's you edit the element's inner HTML in a WYSIWYG manner. You can get the content by automation calls (check bsalsa.com to see how to read the edited content). If you get the basics it is pretty simple to create a full blown HTML editor.
Good luck!