LIST PAGES AND CATEGORIES IN A DROP DOWN MENU, EXCLUDING CERTAIN CATEGORIES AND LIMIT THE NUMBER OF SUB CATEGORIES

<ul> <?php wp_list_categories('orderby=ID&order=ASC&depth=3&title_li=&exclude='); ?> </ul>

Display a tag cloud

Add a cloud of tags used in your blog entries, with words sized based on their frequency. If you tag your entries around a particular area of interest (e.g. web design), this will put some good keywords on your page for search engines as well as making it easy for visitors to locate posts on a specific topic.
Simply add this code to your sidebar (or footer, if you prefer):

<?php wp_tag_cloud('number=15, smallest=6&largest=16&'); ?>

Display archives in a drop down list

If your blog’s been going for a while you’ll want to free up some sidebar space by converting your archive list into a drop down menu. Even if you’ve only had a blog for a few months, putting your archive links in a drop down stops your visitors being drawn away from the rest of your sidebar content.
Just paste this code into your sidebar:

<select name="archive-dropdown" onChange='document.location.href=this.options[this.selectedIndex].value;'>
<option value=""><?php echo attribute_escape(__('Select Month')); ?></option>
<?php wp_get_archives('type=monthly&format=option&show_post_count=1'); ?>
</select>

Display Top Comments

<?php $result = $wpdb->get_results("SELECT comment_count,ID,post_title FROM $wpdb->posts ORDER BY comment_count DESC LIMIT 0 , 10");
foreach ($result as $topten) {
$postid = $topten->ID;
$title = $topten->post_title;
$commentcount = $topten->comment_count;
if ($commentcount != 0) { ?>
<li><a href="<?php echo get_permalink($postid); ?>" title="<?php echo $title ?>"><?php echo $title ?></a></li>
<?php } } ?>

Display a Pages Menu in your Sidebar

<h2>Pages</h2>
<ul>
<?php wp_list_pages('title_li='); ?>
</ul>