So do I, but it must be possible. I mean, unless you have to use CGI, but PHP should be able to do it, too.
http://validator.w3.org/ searches through the source of a specific URI (or an uploaded temporary file, but I know how to do that).
There is another site that checks spelling, links, etc., etc. on a Web page you specify. How do I make PHP follow links from page to page and write out the results (example: visit somesite.com, find all of the links on the page, print them all out, go to each one of those pages individually and print them out, etc.).
That's what I meant.... lol :p