WordPressMU modifiable html theme

On our digital city we are in the process of changing from greymatter to WordPressMU. If possible we would like to have a modifiable theme in html to give our users te oportunity to modify their own theme without the potential dangers of PHP for instance http://www.dse.nl/~falcon/wordpress/ should have the same look as this http://www.rienvalk.dse.nl Is there such a theme or is it makeable?
Kind regards