$(document).ready(function(){ 

$(".message_list .message_body:gt(0)").hide(); 

$(".message_list li:gt(4)").hide(); 
$(".message_head").click(function(){ 
$(this).next(".message_body").slideToggle(500) 
return false; 
}); 

//收起所有消息 
$(".collpase_all_message").click(function(){ 
$(".message_body").slideUp(500) 
return false; 
}); 

//显示所有消息 
$(".show_all_message").click(function(){ 
$(this).hide() 
$(".show_recent_only").show() 
$(".message_list li:gt(4)").slideDown() 
return false; 
}); 

//只显示最近的消息 
$(".show_recent_only").click(function(){ 
$(this).hide() 
$(".show_all_message").show() 
$(".message_list li:gt(4)").slideUp() 
return false; 
}); 

});

* { 
margin: 0; 
padding: 0; 
} 
body { 
margin: 10px auto; 
width: 570px; 
font: 75%/120% Arial, Helvetica, sans-serif; 
} 
p { 
padding: 0 0 1em; 
} 
.message_list { 
list-style: none; 
margin: 0; 
padding: 0; 
width: 383px; 
} 
.message_list li { 
padding: 0; 
margin: 0; 
background: url(images/message-bar.gif) no-repeat; 
} 
.message_head { 
padding: 5px 10px; 
cursor: pointer; 
position: relative; 
} 
.message_head .timestamp { 
color: #666666; 
font-size: 95%; 
position: absolute; 
right: 10px; 
top: 5px; 
} 
.message_head cite { 
font-size: 100%; 
font-weight: bold; 
font-style: normal; 
} 
.message_body { 
padding: 5px 10px 15px; 
} 
.collapse_buttons { 
text-align: right; 
border-top: solid 1px #e4e4e4; 
padding: 5px 0; 
width: 383px; 
} 
.collapse_buttons a { 
margin-left: 15px; 
float: right; 
} 
.show_all_message { 
background: url(images/tall-down-arrow.gif) no-repeat right center; 
padding-right: 12px; 
} 
.show_recent_only { 
display: none; 
background: url(images/tall-up-arrow.gif) no-repeat right center; 
padding-right: 12px; 
} 
.collpase_all_message { 
background: url(images/collapse-all.gif) no-repeat right center; 
padding-right: 12px; 
color: #666666;
}

<ol class="message_list"> 
<li> 
<p class="message_head"><cite>张三:</cite> <span class="timestamp">1分钟前</span></p> 
<div class="message_body"> 
<p>你好<br /> 
<br /> 
这是最后一条消息</p> 
</div> 
</li> 
<li> 
<p class="message_head"><cite>李四:</cite> <span class="timestamp">2分钟前</span></p> 
<div class="message_body"> 
<p>你也好</p> 
</div> 
</li> 
<li> 
<p class="message_head"><cite>王五:</cite> <span class="timestamp">1天前</span></p> 
<div class="message_body"> 
<p>第一次来</p> 
</div> 
</li> 
<li> 
<p class="message_head"><cite>李四:</cite> <span class="timestamp">2天前</span></p> 
<div class="message_body"> 
<p>顶</p> 
</div> 
</li> 
<li> 
<p class="message_head"><cite>王五:</cite> <span class="timestamp">3天前</span></p> 
<div class="message_body"> 
<p>支持</p> 
</div> 
</li> 
<li> 
<p class="message_head"><cite>李四:</cite> <span class="timestamp">5天前</span></p> 
<div class="message_body"> 
<p>大家好</p> 
</div> 
</li> 
<li> 
<p class="message_head"><cite>张三:</cite> <span class="timestamp">6 天前</span></p> 
<div class="message_body"> 
<p>大家好</p> 
</div> 
</li> 
<li> 
<p class="message_head"><cite>李四:</cite> <span class="timestamp">7天前</span></p> 
<div class="message_body"> 
<p>这里不错哦</p> 
</div> 
</li> 
<li> 
<p class="message_head"><cite>王五:</cite> <span class="timestamp">8 天前</span></p> 
<div class="message_body"> 
<p>好地方</p> 
</div> 
</li> 
</ol> 
<p class="collapse_buttons"><a href="#" class="show_all_message">显示所有消息(9)</a> <a href="#" class="show_recent_only">只显示五条消息</a> <a href="#" class="collpase_all_message">收起所有消息</a></p> 
<br />