[Handbag]

It's easy to insert in the thread tools.

Open showthread and search for

<if condition="$show['addpoll']">
	<tr>
		<td class="vbmenu_option"><img class="inlineimg" src="$stylevar[imgdir_button]/addpoll.gif" alt="$vbphrase[add_a_poll]" /> <a href="poll.php?$session[sessionurl]do=newpoll&amp;t=$threadinfo[threadid]">$vbphrase[add_a_poll_to_this_thread]</a></td>
	</tr>
	</if>

Underneath it paste:

<tr>
		<td class="vbmenu_option"><img class="inlineimg" src="http://www.yoursite.com/resizeddeliciouslogo.jpg" alt="Del.icio.us" /> <a href="http://del.icio.us/post?url=$vboptions[bburl]/showthread.php?t=$thread[threadid]&title=$thread[title]" target="_blank">Bookmark with Del.icio.us</a></td>
	</tr>

I screenshoted their fullsize logo and resized it

I wouldn't apply any conditionals because you want as many people as possible bookmarking your links.

You could also add this to any other pulldown menu - could have individual forums bookmarkable too!

You'd probably want to remove the image to fit in wit hthe forum tools pulldown and go to forumdisplay, search for:

<tr><td class="vbmenu_option"><a href="subscription.php?$session[sessionurl]do=addsubscription&amp;f=$foruminfo[forumid]" rel="nofollow">$vbphrase[subscribe_to_this_forum]</a></td></tr>

and paste after (or after/before any of the chunks of code there depending on the order you want to achieve)

<tr>
		<td class="vbmenu_option"><a href="http://del.icio.us/post?url=$vboptions[bburl]/forumdisplay.php?f=$foruminfo[forumid]" target="_blank">Bookmark with Del.icio.us</a></td>
	</tr>