You can quickly locate items in your library or a playlist.

As you type, iTunes displays a list of items that match the criteria you entered. To see your search results in the main iTunes window, press the Return key.

Note: The search behavior has been enhanced in iTunes 11. If you simply start typing, your search results appear in a menu under the Search field, listing the songs, albums, movies, or apps that include those search terms. If you press the Return key, the then category-specific results will display in the main iTunes window.