Actually, in HTML (up to and including HTML 4.01), a / will close the latest tag left open. One example would be the following:
Code html4strict:
<p/This is a paragraph/
<p/This is another paragraph/
<!-- ignore the following code - SitePoint is having problems with null end tags, it seems ;) -->
This is equivilant to the following:
Code html4strict:
<p>This is a paragraph</p>
<p>This is another paragraph</p>
The disadvantage is, of course, that you can't use a / without escaping it.

Since the > doesn't have to be escaped, unlike the < and the &, this syntax:
Code html4strict:
<p/> means greater than/
is equivilant to
Code html4strict:
<p>> means greater than</p>

There are also other SGML shorthand methods. A few examples can be seen in my signature, which is equivilant to:
Code html4strict:
<p><strong><abbr>HTML</abbr> 4 teh win</strong></p>
<p>In Soviet Russia, website codes you!</p>

Unfortunately, no mainstream user agents actually conform to this. Still, the official HTML validator will correctly validate such shorthand syntax.