<blockquote>
  <p><strong>Possible Duplicates:</strong><br />
  <a href="http://meta.stackexchange.com/questions/10802/can-you-add-a-math-related-site-to-the-trilogy">Can you add a math related site to the &ldquo;Trilogy&rdquo;?</a><br />
  <a href="http://meta.stackexchange.com/questions/806/-stackoverflow-com">*.Stackoverflow.com</a>  </p>
</blockquote>

<p>I can think of a couple:</p>

<ol>
<li><p>"Math Overflow" - math is generally not subjective and questions can be answered in a straightforward manner, but the questions do not necessarily belong on Stack Overflow because often they aren't programming-related.</p></li>
<li><p>A goof-off site. One where the users are not directed to follow any specific category or subject, and can post whatever they want. This will undoubtedly result in a lot of humor and nonsense, but would certainly make for good entertainment.</p></li>
</ol>