If you are using IE7 and accessing this blog directly - you will notice that the drop down arrow in the Toolbar Search Box (in the top right) has lit up orange to flag that it has discovered a new search provider i.e. the search of this blog. From here you can add the discovered search provider so its accessible at anytime.



If you look in the source of the HTML page you will see the link item :

link title="Mark Harrison blog" type="application/opensearchdescription+xml" rel="search" href="http://markharrison.co.uk/blog/Mark_Harrison_Blog_Search.xml"

The href points to a file that was generated using the IE7 Search Provider builder