Hi there - I work on del.icio.us, and I think the del.icio.us widget on wordpress.com blogs is misbehaving and might need a tweak.
We're seeing metric craploads of feed requests like this with *.wordpress.com referers:
http://del.icio.us/feeds/json//?count=0;
Looking at a random wordpress.com blog (http://komiksnewsnow.wordpress.com/), I see this apparently invisible code snippet:
<li id="delicious" class="widget widget_delicious">
<h2 class="widgettitle"><a href='http://del.icio.us/'></a></h2>
<div id="delicious-box" class="snap_preview" style="margin:0;padding:0;border:none;"> </div>
<script type="text/javascript" src="http://del.icio.us/feeds/json//?count=0;"></script>