.Gnb_btn_div{
 width:90px;
 height:75px;
 overflow:hidden;
 display:block;
 position:absolute;
}   

.Gnb_btn_img{
 width:100%;
 height:525px;
 display:block;
 overflow:hidden;
 text-indent:-500px;
}
#gnb_btn_01 .Gnb_btn_img {
 background-image:url(http://www.syku.net/web/UploadFiles_5065/200801/20080122113914201.gif)
}

以下是代码片段：

<script type="text/javascript">
// <![CDATA[
function GNB(_7c){
 //初始化一些参数
 this.iImgNum=7;   //小图片个数
 this.iImgHeight=75;  //小图片高度
 this.iOverSpeed=50;  //鼠标经过时候切换的时间
 this.iOutSpeed=50;  //鼠标离开时候切换的时间
 this.eventObj=_7c;  //取得图片对象   

 this.MouseOverFlag=false;
 this.imageIndex=0;
 if(this.eventObj==null){return;}
 this.eventObj.parentClass=this;this.eventAssign();
}   

GNB.prototype.eventAssign=function(){//注册事件
 this.eventObj.onmouseover=this.menuMouseOver;
 this.eventObj.onmouseout=this.menuMouseOut;
};   

GNB.prototype.menuMouseOver=function(){//鼠标经过
 if(this.parentClass.MouseOverFlag!=false){return;}
 this.parentClass.MouseOverFlag=true;
 this.parentClass.clearTimeOut();
 this.parentClass.menuMouseOverTimer();
};   

GNB.prototype.menuMouseOut=function(){//鼠标离开
 this.parentClass.MouseOverFlag=false;
 this.parentClass.clearTimeOut();
 this.parentClass.menuMouseOutTimer();
};   

GNB.prototype.menuMouseOverTimer=function(){//经过图片位置递增
 var _7d=this;
 if(this.imageIndex>=this.iImgNum){return;}
 this.eventObj.scrollTop=this.imageIndex*this.iImgHeight;
 this.imageIndex++;
 this.setTimerID=setTimeout(function(){_7d.menuMouseOverTimer();},this.iOverSpeed);
};   

GNB.prototype.menuMouseOutTimer=function(){////经过图片位置递减
 var _7e=this;if(this.imageIndex<0){return;}
 this.eventObj.scrollTop=this.imageIndex*this.iImgHeight;
 this.imageIndex--;
 this.setTimerID=setTimeout(function(){_7e.menuMouseOutTimer();},this.iOutSpeed);
};   

GNB.prototype.clearTimeOut=function(){//取消定时
 clearTimeout(this.setTimerID);
};
// ]]>
</script>

<div class="Gnb_btn_div" id="gnb_btn_01">
<a class="Gnb_btn_img" href="#1" mce_href="#1">找朋友</a>
</div>   

<script type="text/javascript">
// <![CDATA[
var GNB1=new GNB(document.getElementById("gnb_btn_01"));//实例单个按钮,当然也可以多个
// ]]>
</script>