Dublin Core and eGMS Metadata Viewer for Firefox
Firefox add-in for displaying Dublin Core and eGMS metadata embedded in META and LINK elements of HTML/XHTML document headers. Slightly wackily, it will also display metadata from the NASA taxonomy too.
Click here to install the add-on. The most recent release was on 2 August 2010. It is available under the terms of the Creative Commons Attribution-ShareAlike license, and the source code is available on request.
This add-on is based on an earlier Dublin Core Viewer written by Patrick Lauke. I don't claim to be an expert on any of this stuff, but I responded to a Twitter suggestion by Andy Mabbett, eGMS being a handy thing for local and national government officers, apparently. It would be straightforward to add other Dublin Core based vocabularies, so do get in touch if you have a suggestion.