I am sure there may be a few that exist. I have not had any experience with either but take a look at the below links:
iPad HTML Editor - http://itunes.apple.com/us/app/kytekhtmleditor/id349354394?mt=8
SquareSpace for iPad - http://mashable.com/2010/12/21/squarespace-ipad/
Check out the following Web (html) Wysiwyg Editors.:
Dreamweaver
Flux (Mac only)
Creative Suite
Expression Web/Studio
There are a quite few available WYSIWYG editors and some are even free. However, 'free' is not always best as the code compilation may not be optimal and important features are lacking.
Hope that helps!
