<p>Another option is to use <a href="http://mathurl.com/" rel="nofollow">http://mathurl.com/</a>, and then link to the picture.</p>

<p><img src="http://mathurl.com/2aswtnm.png" alt="alt text"></p>

<p>See <a href="http://www.or-exchange.com/questions/219/what-file-format-for-problem-definition-is-suitable-for-or-exchange/224#224" rel="nofollow">this discussion</a>.</p>

<p>According to the site's about section:</p>

<blockquote>
  <p>This short link will now forever refer to your equation!</p>
</blockquote>
