eBay recently added Search Expansions to the site's search functionality. With search expansions, when someone uses the search box to find a particular type of item, eBay will now display those listings that have the keyword in the title as usual as well as displaying all items in a relevant category that eBay has mapped to the keyword.

In eBay's example,a search for action figure will come back with search results that will show all items with action figure in the title, as well as all items in the Action Figures category. Or, if the buyer types in Superman action figure, eBay will show all listings with Superman action figure in the title, as well as all listings with Superman in the title that are in the Action Figures category.

Users who don't want to have the expanded results shown can use quotation marks around any single keyword in your search terms (for example: "Superman" action figure).

http://www2.ebay.com:80/aw/marketing.shtml#2005-03-14152723