Spawning new pages

I want one of my functions to create and open a new page. I know how to call an existing page from PHP ala form action, but in this case I want to dynamically create and then display several pages. I'm thinking that perhaps I should assemble some HTML, write it out to a files, then open the HTML file. Is this the best way of going about it? Can it be done without actually writing the HTML to the disk? How do I actually open the page once it's been created?