Sticky hack instructions originally written by Mark from Weblog Tools Collection as implemented by LaughingLizard - http://dinki.mine.nu/weblog
Revised for Wordpress 1.2 and added custom icon by Marius Ooms - http://oomsonline.com

Required steps:
STEP 1: Modify Database
STEP 2: Modify wp-blog-header.php
STEP 3: Modify wp-blog-header.php
STEP 4: Modify wp-admin/edit-form.php
STEP 5: Modify wp-admin/edit-form-advanced.php
STEP 6: Modify wp-admin/post.php

DISCLAIMER: Always make a backup of your original files, your are about to modify core code.

________________________________________________________________________________________________________________________________
###STEP 1###____________________________________________________________________________________________________________________

This hack requires a small change to be made to the database. (Offcourse there are different ways to modify your tables.) 

Using phpMyAdmin, find your database. 
Click on wp_posts (could be *anyprefix*_posts). 
Click on Structure
Click on post_status
Find the length/values column where the following line should be present:
	'publish','draft','private','static'
Just add ,'sticky' to the line so the final value looks like so:
	'publish','draft','private','sticky','static' 

________________________________________________________________________________________________________________________________
###STEP 2###____________________________________________________________________________________________________________________

==FIND: Around line 429 in wp-blog-header.php==

if ($pagenow != 'post.php') {
	if ((empty($poststart)) || (empty($postend)) || !($postend > $poststart)) {
		$where .= ' AND post_date <= \''.$now.'\'';
	}

	$distinct = 'DISTINCT';

	if ($use_gzipcompression) {
		// gzipping the output of the script
		gzip_compression();
	}
}
$where .= ' AND (post_status = "publish"';

// Get private posts
if (isset($user_ID) && ('' != intval($user_ID)))
    $where .= " OR post_author = $user_ID AND post_status != 'draft')";
else
    $where .= ')';
$request = " SELECT $distinct * FROM $tableposts $join WHERE 1=1".$where." ORDER BY post_$orderby $limits";

________________________________________________________________________________________________________________________________

==REPLACE: Replace with this==

if ($pagenow != 'post.php') {
	if ((empty($poststart)) || (empty($postend)) || !($postend > $poststart)) {
		$where .= ' AND post_date <= \''.$now.'\'';
	}

	$distinct = 'DISTINCT';

	if ($use_gzipcompression) {
		// gzipping the output of the script
		gzip_compression();
	}
}
$where .= ' AND (post_status = "publish" OR post_status = "sticky"';

// Get private posts
if (isset($user_ID) && ('' != intval($user_ID)))
    $where .= " OR post_author = $user_ID AND post_status != 'draft')";
else
    $where .= ')';
$request = " SELECT $distinct * FROM $tableposts $join WHERE 1=1".$where." ORDER BY post_status DESC, post_$orderby $limits";

________________________________________________________________________________________________________________________________
###STEP 3###____________________________________________________________________________________________________________________

==FIND: Around line 483 in wp-blog-header.php==
    
	$comment_counts = $wpdb->get_results("SELECT ID, COUNT( comment_ID ) AS ccount
        FROM $tableposts
        LEFT JOIN $tablecomments ON ( comment_post_ID = ID  AND comment_approved =  '1')
        WHERE post_status =  'publish' AND ID IN ($post_id_list)
        GROUP BY ID");
        
________________________________________________________________________________________________________________________________

==REPLACE: Replace with this==

    $comment_counts = $wpdb->get_results("SELECT ID, COUNT( comment_ID ) AS ccount
        FROM $tableposts
        LEFT JOIN $tablecomments ON ( comment_post_ID = ID  AND comment_approved =  '1')
        WHERE (post_status =  'publish' OR post_status = 'sticky') AND ID IN ($post_id_list)
        GROUP BY ID");
        
________________________________________________________________________________________________________________________________     
###STEP 4### ___________________________________________________________________________________________________________________

==FIND: Around line 95 in wp-admin/edit-form.php==

  <input name="saveasprivate" type="submit" id="saveasprivate" tabindex="10" value="Save as Private" /> 

________________________________________________________________________________________________________________________________

==ADD: Add this below it==

  <input name="saveassticky" type="submit" id="saveassticky" tabindex="10" value="Publish as Sticky" /> 

________________________________________________________________________________________________________________________________
###STEP 5###____________________________________________________________________________________________________________________

==FIND: Around line 78 in wp-admin/edit-form-advanced.php==

	<fieldset id="poststatusdiv">
      <legend><a href="http://wordpress.org/docs/reference/post/#post_status" title="Help on post status">Post Status</a></legend>
	  <div><label for="post_status_publish" class="selectit"><input id="post_status_publish" name="post_status" type="radio" value="publish" <?php checked($post_status, 'publish'); ?> /> Publish</label> 
	  <label for="post_status_draft" class="selectit"><input id="post_status_draft" name="post_status" type="radio" value="draft" <?php checked($post_status, 'draft'); ?> /> Draft</label> 
	  <label for="post_status_private" class="selectit"><input id="post_status_private" name="post_status" type="radio" value="private" <?php checked($post_status, 'private'); ?> /> Private</label></div>
    </fieldset>

________________________________________________________________________________________________________________________________

==REPLACE: Replace with this==
    
	<fieldset id="poststatusdiv">
      <legend><a href="http://wordpress.org/docs/reference/post/#post_status" title="Help on post status">Post Status</a></legend>
	  <div><label for="post_status_publish" class="selectit"><input id="post_status_publish" name="post_status" type="radio" value="publish" <?php checked($post_status, 'publish'); ?> /> Publish</label> 
	  <label for="post_status_draft" class="selectit"><input id="post_status_draft" name="post_status" type="radio" value="draft" <?php checked($post_status, 'draft'); ?> /> Draft</label> 
	  <label for="post_status_private" class="selectit"><input id="post_status_private" name="post_status" type="radio" value="private" <?php checked($post_status, 'private'); ?> /> Private</label>
	  <label for="post_status_sticky" class="selectit"><input id="post_status_sticky" name="post_status" type="radio" value="sticky" <?php checked($post_status, 'sticky'); ?> /> Sticky</label></div>    		
    </fieldset>

________________________________________________________________________________________________________________________________
###STEP 6###____________________________________________________________________________________________________________________

==FIND: Around line 105 in wp-admin/post.php==

	if ('' != $_POST['saveasprivate']) $post_status = 'private';

________________________________________________________________________________________________________________________________

==ADD: Add this below it==

	if ('' != $_POST['saveassticky']) $post_status = 'sticky';
	
________________________________________________________________________________________________________________________________
###CUSTOMIZED ICON###___________________________________________________________________________________________________________

To insert a custom icon like here, oomsonline.com, make these addititons.

==FIND: Around line 39 (Default Install) in index.php==

	<h3 class="storytitle" id="post-<?php the_ID(); ?>"><a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link: <?php the_title(); ?>"><?php the_title(); ?></a></h3> 

________________________________________________________________________________________________________________________________

==ADD: Add this above that line==

	<?php if ($post->post_status == 'sticky') echo '<div id="sticky">'; ?>

________________________________________________________________________________________________________________________________

==ADD: Add this below that line==

	<?php if ($post->post_status == 'sticky') echo '</div>'; ?>

________________________________________________________________________________________________________________________________
DISCLAIMER, DO NOT COPY AND PASTE CODE BELOW. 
This is how my entry section looks like. My index.php is very customized so it might not work for you: 

		<?php if ($posts) : foreach ($posts as $post) : start_wp(); ?>
			
			<?php if ($post->post_status == 'sticky') echo '<div id="sticky">'; ?>
			<div class="title" id="post-<?php the_ID(); ?>"><?php the_title(); ?></div>
			<?php if ($post->post_status == 'sticky') echo '</div>'; ?>
			
			<div class="date"><?php the_date('','',''); ?> posted <?php the_time() ?></div>
			<div class="bodytext"><?php the_content(); ?></div>		
			
			<div class="postread">
				<?php wp_link_pages(); ?>
				<?php comments_popup_link(__('/ 0 posts so far'), __('/ 1 post, making progress'), __('/ % posts, gotta read this')); ?>
			</div><div class="hr"></div><hr /><p>

			<?php include(ABSPATH . 'wp-comments.php'); ?>
			
		<?php endforeach; else: ?>
		
		<?php endif; ?>

Modify your style sheet, my entry looks like this:

	#sticky {
		background-image: url(../images/icons/sticky.gif);
		background-repeat:no-repeat;
		background-position: 310px 0px;
		height: 19px;
		}


All done!

Now to implement this hack, simply choose "sticky" as the post option in a post and it will show up on
top of your blog no matter what time or date it is. To remove the sticky, simply edit the post and change
the status back to publish.