Some of the sites I use most don't support the very nice feature of OpenSearch discovery links. Among these are Flickr and Google Maps - so I first have to navigate to Flickr, then search rather than doing it straight from the browser quick search area.

Fortunately, someone has provided this for me. Just go to http://mvinetwork.co.uk/opensearch/ and click open your OpenSearch discovery and add whatever engines you want!

Hopefully more services that already can support OpenSearch templating add the necessary and simple descriptions and discovery links.

For extra credit, you could extend the OpenSearch definition for GMaps to support location name: http://maps.google.com/maps?q={searchTerms}&hnear={geo:locationString?} - and even Flickr supports (and was the model for) OpenSearch-Geo box search.