title: Hidden features of Greasemonkey
body: <p>What are some of the lesser-known but useful features and techniques that people are using in their Greasemonkey scripts?</p>
  
  <p>(Please, just one feature per answer.)</p>
  
  <p>Similar threads:</p>
  
  <ul>
  <li><a href="https://stackoverflow.com/questions/61088/hidden-features-of-javascript">Hidden Features of JavaScript</a></li>
  <li><a href="https://stackoverflow.com/questions/15496/hidden-features-of-java">Hidden Features of Java</a></li>
  <li><a href="https://stackoverflow.com/questions/75538/hidden-features-of-c">Hidden Features of C++</a></li>
  <li><a href="https://stackoverflow.com/questions/9033/hidden-features-of-c">Hidden Features of C#</a></li>
  </ul>