Perma-Closing Message Boxes with JavaScript + CSS
http://www.cssnewbie.com/message-box-javascript-css/

Glazebrook, Rob L.
CSSnewbie
2008

Abstract:

Earlier this week I talked a bit about message boxes – how to style them and position them on your page to get them noticed. But a message that pops up every single time your website is loaded could get annoying. It’d be useful to give your users the ability to close those messages. For that, we’ll turn to our friend JavaScript.