This add-on is based on SimpleSuggest, adding a search suggestion to your OsCommerce search box,
but it also records each customers' searched keywords and sort the result products order by
popular search, or even simply show the result in term of popular keywords.
It also gives the ability to search in multiple keywords using AND/OR.
Options can be set in Admin and automatically install and deal with database.
Support thread: http://forums.oscommerce.com/topic/394763-smartsuggest-self-learning-ajax-search-suggestion/