android widget

讲解得很详细：

http://www.cnblogs.com/TerryBlog/archive/2010/07/29/1788319.html

http://blog.csdn.net/meshless/article/details/6963670

扩展部分较好：

http://wenku.baidu.com/view/9de5ee1314791711cc7917f9.html

便签widget:

http://blog.csdn.net/silenceburn/article/details/6093074