Many of us use social bookmarking sites -- del.icio.us, digg, reddit, etc.  They're pretty useful, and also great sources of organic traffic.  There are plenty of plugins for blogging applications that place icons on a page to ease its bookmarking.  For example, the one I use for this WordPress blog is  called "Sociable."

But that's for WordPress.  I wanted to experiment with social bookmarking on some of the custom sites I develop, so I developed a little class that will work for any web application.  I took the icons and referenced the list of sites from Sociable, so kudos to Peter Harkins for putting all that stuff together.  Here it is:

<?

// +----------------------------------------------------------------------+
// | SocialBookmarking                                                    |
// | Displays links for various social bookmarking services               |
// +----------------------------------------------------------------------+
// | Copyright (c) 2005 Jaimie Sirovich                                   |
// +----------------------------------------------------------------------+
// | Author: Jaimie Sirovich <jsirovic@gmail.com>                         |
// | Icons taken from WordPress Plugin Sociable by Peter Harkins          |
// | (http://push.cx)                                                     |
// +----------------------------------------------------------------------+

class SocialBookmarking
{
    var $_link;
    var $_title;
    var $_site_name;
    
    var $_templates = array(
    
        'blinkbits' => array(
            'icon' => 'blinkbits.png',
            'url' => 'http://www.blinkbits.com/bookmarklets/save.php?v=1&source_url={LINK}&title={TITLE}&body={TITLE}',
        ),
    
        'BlinkList' => array(
            'icon' => 'blinklist.png',
            'url' => 'http://www.blinklist.com/index.php?Action=Blink/addblink.php&Description=&Url={LINK}&Title={TITLE}',
        ),
    
        'blogmarks' => array(
            'icon' => 'blogmarks.png',
            'url' => 'http://blogmarks.net/my/new.php?mini=1&simple=1&url={LINK}&title={TITLE}',
        ),
    
        'co.mments' => array(
            'icon' => 'co.mments.gif',
            'url' => 'http://co.mments.com/track?url={LINK}&title={TITLE}',
        ),
    
        'connotea' => array(
            'icon' => 'connotea.png',
            'url' => 'http://www.connotea.org/addpopup?continue=confirm&uri={LINK}&title={TITLE}',
        ),
    
        'del.icio.us' => array(
            'icon' => 'delicious.png',
            'url' => 'http://del.icio.us/post?url={LINK}&title={TITLE}',
        ),
    
        'De.lirio.us' => array(
            'icon' => 'delirious.png',
            'url' => 'http://de.lirio.us/rubric/post?uri={LINK};title={TITLE};when_done=go_back',
        ),
    
        'digg' => array(
            'icon' => 'digg.png',
            'url' => 'http://digg.com/submit?phase=2&url={LINK}&title={TITLE}',
        ),
    
        'Fark' => array(
            'icon' => 'fark.png',
            'url' => 'http://cgi.fark.com/cgi/fark/edit.pl?new_url={LINK}&new_comment={TITLE}&new_comment={SITENAME}&linktype=Misc',
        ),
    
        'feedmelinks' => array(
            'icon' => 'feedmelinks.png',
            'url' => 'http://feedmelinks.com/categorize?from=toolbar&op=submit&url={LINK}&name={TITLE}',
        ),
    
        'Furl' => array(
            'icon' => 'furl.png',
            'url' => 'http://www.furl.net/storeIt.jsp?u={LINK}&t={TITLE}',
        ),
    
        'LinkaGoGo' => array(
            'icon' => 'linkagogo.png',
            'url' => 'http://www.linkagogo.com/go/AddNoPopup?url={LINK}&title={TITLE}',
        ),
    
        'Ma.gnolia' => array(
            'icon' => 'magnolia.png',
            'url' => 'http://ma.gnolia.com/beta/bookmarklet/add?url={LINK}&title={TITLE}&description={TITLE}',
        ),
    
        'NewsVine' => array(
            'icon' => 'newsvine.png',
            'url' => 'http://www.newsvine.com/_tools/seed&save?u={LINK}&h={TITLE}',
        ),
    
        'Netvouz' => array(
            'icon' => 'netvouz.png',
            'url' => 'http://www.netvouz.com/action/submitBookmark?url={LINK}&title={TITLE}&description={TITLE}',
        ),
    
        'RawSugar' => array(
            'icon' => 'rawsugar.png',
            'url' => 'http://www.rawsugar.com/tagger/?turl={LINK}&tttl=TITTLE',
        ),
        
        'Reddit' => array(
            'icon' => 'reddit.png',
            'url' => 'http://reddit.com/submit?url={LINK}&title={TITLE}',
        ),
    
        'scuttle' => array(
            'icon' => 'scuttle.png',
            'url' => 'http://www.scuttle.org/bookmarks.php/maxpower?action=add&address={LINK}&title={TITLE}&description={TITLE}',
        ),
    
        'Shadows' => array(
            'icon' => 'shadows.png',
            'url' => 'http://www.shadows.com/features/tcr.htm?url={LINK}&title={TITLE}',
        ),
    
        'Simpy' => array(
            'icon' => 'simpy.png',
            'url' => 'http://www.simpy.com/simpy/LinkAdd.do?href={LINK}&title={TITLE}',
        ),
    
        'Smarking' => array(
            'icon' => 'smarking.png',
            'url' => 'http://smarking.com/editbookmark/?url={LINK}&description={TITLE}',
        ),
    
        'Spurl' => array(
            'icon' => 'spurl.png',
            'url' => 'http://www.spurl.net/spurl.php?url={LINK}&title={TITLE}',
        ),
    
        'TailRank' => array(
            'icon' => 'tailrank.png',
            'url' => 'http://tailrank.com/share/?text=&link_href={LINK}&title={TITLE}',
        ),
    
        'Wists' => array(
            'icon' => 'wists.png',
            'url' => 'http://wists.com/r.php?c=&r={LINK}&title={TITLE}',
        ),
    
        'YahooMyWeb' => array(
            'icon' => 'yahoomyweb.png',
            'url' => 'http://myweb2.search.yahoo.com/myresults/bookmarklet?u={LINK}&={TITLE}',
        )
    
    );
    
    function SocialBookmarking($link, $title, $site_name)
    {
        $this->_link = $link;
        $this->_title = $title;
        $this->_site_name = $site_name;
    }

    function getHTML($sites = array('del.icio.us', 'digg', 'Furl', 'Reddit', 'YahooMyWeb'))
    {
        
        $tmp = "<ul class=\"social_bookmarking\">";
        
        foreach($sites as $s) {
            
            if ($_site_info = $this->_templates[$s]) {
    
                $tmp .= "<li class=\"social_bookmarking\">";
        
                $url = str_replace(array('{LINK}', '{TITLE}', '{SITENAME}'), array(urlencode($this->_link), urlencode($this->_title), urlencode($this->_site_name)), $_site_info['url']); 

                $tmp .= "<a rel=\"nofollow\" href=\"$url\" title=\"$s\">";
                $tmp .= "<img src=\"/social_bookmarking_icons/{$_site_info['icon']}\" alt=\"$s\" class=\"social_bookmarking\" />";
                $tmp .= "</a></li>";
            
            }
                        
        }
        
        $tmp .= "</ul>";
        
        return $tmp;
        
    }

}

?>

You'll need to place these icons in the directory "/social_bookmarking_icons" on your web server.  You may also want to set up styles for the elements of class "social_bookmarking."

To use it, simply create a class by calling the constructor with parameters link, title, and site name.  Then make a call to "getHTML()."  Now you're done!