Karma - When searching on the infamous “90210” ZIP code, Karma gives the user a quote from its namesake TV show.
/via Patrick H.
Mac OS X Mountain Lion Spotlight - Finds Calendar & Contacts even when you type in their old names (iCal & Address Book) from previous versions of Mac OS X.
Apple - searching for colloquial or rumored product names (such as iTouch or iTablet) refers you to the appropriate products.
Facebook - When you have your relatives marked on Facebook, you can search for them by their relation to you.
/via Ian Arthur Spaeth
Make me a Cocktail - If you click on the search button with nothing in the search box, it types out a random cocktail for you to try.
/via Nick Wilkins
iTunes - Lets you filter song rating by typing asterisk symbols in search bar
Meetup.com - When there are no results within a particular distance, the search distance expands until it can find a result.
/via Michael J. Morgan
Designspiration - Just start typing any letters or numbers to begin a search query.
/via Pierre Valade
Google+ - When searching, the page indicator arrow slides from the left side to the top.
/via Vedran Židanik