Somebody once said that the best ideas are the most simple ones.
Here comes one I had this morning when asked for example of page using this or that paragraph in Magnolia:
select * from nt:base where mgnl:template = 'stkTeaser'
Login to Admin Central, go to the JCR Queries, set target repository to website, limit result types to mgnl:content and type in the query above.
Of course, also...