i already use html comments in my nodes -- i keep some tags handy in my sig (below.) every once in a while i'll add a keyword or phrase to a node so i can google with confidence. it would be nice to have some supported tags, but you can at least track your own nodes by implementing this method yourself... i already do :)

<!-- a handy place to keep tags 
<code>
.
</code >
<blockquote><em>.</em></blockquote>
<strong>.</strong>
<ul>
 <li>.</li>
 <li>.</li>
</ul>
-->
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~Particle *accelerates*