Flash, Frames and JavaScript
To humans they look great but to Search engines Macromedia Flash, frames and JavaScript are meaningless. In fact, some of the robots and spiders stop completely when they encounter script on a page. But look at the source of the majority of Web pages and where do you find the JavaScript? If you construct your header to impart the maximum of information then spider will have found enough useful material ahead of the script to give you a meaningful entry.