个人认为比较有用的jquery插件

菜单类：

http://www.designchemical.com/blog/index.php/frequently-asked-questions/floating-menu/
 

http://www.sitepoint.com/make-a-mega-drop-down-menu-with-jquery/
 

树：

ztree

http://www.baby666.cn/v3/demo.php#_101
 

表格

jqGrid
 

http://www.trirand.com/blog/jqgrid/jqgrid.html

信息提示插件
 

http://code.drewwilson.com/entry/tiptip-jquery-plugin

http://gdakram.github.com/JQuery-Tooltip-Plugin/
 

jQuery的UI工具包 jQuery Tools
 

http://jquerytools.org/