Markzware, creators of the popular Q2ID, ID2Q and PUB2ID file conversion plug-ins, has just released PageZephyr, a Macintosh-only program that will index your Quark 6 (or newer) and InDesign CS (or newer) files, and then allow you to search and view the text content in the files, and extract the found content to RTF or TXT files.
Potential uses include: quickly locating layout files based on content on a large storage volume, quick text extraction for repurposing or archiving content, or sifting through large volumes of Quark and InDesign content for legal discovery purposes.
I'll be evaluating PageZephyr in the near future, and will provide a more detailed post soon.
* Full disclosure: I'm a Markzware affiliate. This means that if you visit their site from here, and eventually buy something, I might make a few bucks. Thanks.