We had a case where some content owners copied content from the old site (straight from IE) into the placeholders for the new site. Let me say one thing about that: tell your content owners NOT to do that. Why? Think of image links: they won't be the same, but the URLs will be pointing back to the old site... scary! So we needed a utility that would tear through all text placeholders (Html & Xml) and search for a specific string. I wrote this little utility and it damn sure helped me!
[Update 10/31/2008 @ 1:50p] Reposted this utility to MSDN Code Gallery. More info in this blog post: Blast from the past: AC's MCMS Utilities