I just discovered a cool easter egg in Sherlock. Open Sherlock and go to the dictionary. Leave the "word to define" field empty and click the green search button. Although it will say "No results found," you'll also get a list of spelling suggestions that includes zip, nada goose egg, zip, and zilch. The result of searching for "nothing." Cool!
[robg adds: There are so few easter eggs in OS X, I thought this was worth a mention ... and it's clearly something that was added to Sherlock, as a visit directly to either Bartleby.com or Dictionary.com shows that searching for blanks does not return anything at all.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20030407151135701