I'm calling out to a 3rd party SOAP service and the result is returned as an XML string (don't blame me for that, it's what their WSDL file says). I've been tossing that result into a CouchDB doc - it's so easy, you might as well - in case I needed to refer to it later.
That time has come as I now need to be a bit more selective about how I handle the result. So, I fired up CouchDB's Futon and wrote a view that emitted bits of the JSON together with the interesting parts of the XML blob. Now I have a simple view of the data without all the XML "noise". Very nice :).
What's best about this is that using CouchDB, XML and E4X together is trivial and E4X is compact and quick to learn.