I was wondering if there was a tool that could generate geographic extents from the bounding coordinates specified in FGDC-compliant metadata. The intent would be to verify coverage. I know there are probably other ways to do this, but I am curious to know if this is possible.
Yes, it is possible, but you will have to write your own tool.
I did this for some MrSID image extents way back (2004) with ArcGIS 8.3 using the Python SAX module to parse the metadata XML file. You have to define a handler function for each tag that you want to extract using SAX. I have even found the code, which you could have if you really want to go down that route. I see that Open Office still use this method which is very fast for large XML files typical of word documents. I learnt how to do this from an O'Reilly book: Python & XML
It is easier to use the newer ElementTree module. You will need to export the metadata to a file to be able to parse it.