function cut_str($string, $sublen, $start = 0, $code = 'UTF-8'){
	if($code == 'UTF-8'){
		$pa = "/[\x01-\x7f]|[\xc2-\xdf][\x80-\xbf]|\xe0[\xa0-\xbf][\x80-\xbf]|[\xe1-\xef][\x80-\xbf][\x80-\xbf]|\xf0[\x90-\xbf][\x80-\xbf][\x80-\xbf]|[\xf1-\xf7][\x80-\xbf][\x80-\xbf][\x80-\xbf]/";
		preg_match_all($pa, $string, $t_string);
		if(count($t_string[0]) - $start > $sublen) 
			return join('', array_slice($t_string[0], $start, $sublen))."...";
		return join('', array_slice($t_string[0], $start, $sublen));}
	else{
		$start = $start*2;
		$sublen = $sublen*2;
		$strlen = strlen($string);
		$tmpstr = '';
		for($i=0; $i<$strlen; $i++){
			if($i>=$start && $i<($start+$sublen)){
				if(ord(substr($string, $i, 1))>129) 
					$tmpstr.= substr($string, $i, 2);
				else 
					$tmpstr.= substr($string, $i, 1);
			}
			if(ord(substr($string, $i, 1))>129) 
				$i++;
		}
		if(strlen($tmpstr)<$strlen ) 
			$tmpstr.= "...";
		return $tmpstr;
	}
}

<h3>Recent Comments</h3>
	<ul class="recentcomments">
	<?php
		global $wpdb;
		$sql = "SELECT DISTINCT ID, post_title, post_password, comment_ID, comment_post_ID, comment_author, comment_date_gmt, comment_approved, comment_type,comment_author_url,comment_author_email, comment_content AS com_excerpt FROM $wpdb->comments LEFT OUTER JOIN $wpdb->posts ON ($wpdb->comments.comment_post_ID = $wpdb->posts.ID) WHERE comment_approved = '1' AND comment_type = '' AND comment_author_email != '******@ninthday.net' AND post_password = '' ORDER BY comment_date_gmt DESC LIMIT 6";
		$comments = $wpdb->get_results($sql);
		foreach ($comments as $comment) {
			$a= 'http://www.ninthday.net/avatar/'.md5(strtolower($comment->comment_author_email)).'.jpg';
			$output .= "\n<li><img src='". $a ."' alt='Ninthday_Gravatar' title='".$comment->comment_author."' class='avatar avatar-32 photo' /><a href=\"" . htmlspecialchars(get_comment_link( $comment->comment_ID )) . "\" title=\"on " .$comment->post_title . "\">" . cut_str(strip_tags($comment->com_excerpt),14)."</a><br/><span class='commentAuthor'>By".$comment->comment_author."</span></li>";
		}
		$output = convert_smilies($output);
		echo $output;
	?>
	</ul>

#sidebar .recentcomments img.avatar{width:33px;height:33px;float:left;position:relative;border:1px solid #ddd;margin:0 5px 0 0;padding:2px;}
#sidebar ul.recentcomments{list-style:none;padding-left:0;display:block;}
#sidebar ul.recentcomments li{margin:5px 0 0;line-height:16px;height:32px;overflow:hidden;}
#sidebar .commentAuthor{color:#999;}

function my_avatar( $email, $size = '32', $default = '', $alt = '' ) {
	$alt = esc_attr( $alt );
	$f = md5( strtolower( $email ) );
	$w = get_bloginfo('wpurl'); // 如果想放在 wp-content 路徑之下, 改為 $w = WP_CONTENT_URL;
	$a = $w. '/avatar/'. $f. '.jpg';
	$e = ABSPATH. 'avatar/'. $f. '.jpg'; // 如果想放在 wp-content 路徑之下, 改為 $e = WP_CONTENT_DIR. '/avatar/'. $f. '.jpg';
	$t = 1209600; //設定14天, 單位:秒
	if ( empty($default) ) 
		$default = $w. '/avatar/default.jpg';
	if ( !is_file($e) || (time() - filemtime($e)) > $t ){ //當頭像不存在或文件超過14天才更新
		$r = get_option('avatar_rating');
		//$g = sprintf( "http://%d.gravatar.com", ( hexdec( $f{0} ) % 2 ) ). '/avatar/'. $f. '?s='. $size. '&d='. $default. '&r='. $r; // wp 3.0 的服務器
		$g = 'http://www.gravatar.com/avatar/'. $f. '?s='. $size. '&d='. $default. '&r='. $r; // 舊服務器 (哪個快就開哪個)
		copy($g, $e); $a = esc_attr($g); //新頭像 copy 時, 取 gravatar 顯示
	}
	if (filesize($e) < 500) 
		copy($default, $e);
	/* echo "<img title='{$alt}' alt='{$alt}' src='{$a}' class='avatar avatar-{$size} photo' height='{$size}' width='{$size}' />";*/
	echo $a;
}