Program to edit HTML file via the web??

Does anyone have or have some code available that allows a user to edit an HTML web page file over the Internet. I know it would be simple to build a textarea form and read the file into this and edit as necessary them update the file. But I am looking for something with some controls on it, like only reading the HTML between two font tags lets say. This way a user editing the file would not get themselves into trouble by accidentally deleting a table tags for instance. Thanks Everyone Blake S.