In the category of “why didn’t I think of this†comes liveslices.com. Go have a look (obviously after installing IE8RC)
Webslices is one of the new end-user features of IE8. It is easy to implement on your website: I added it to http://www.nickhodge.com/ within minutes. Some microformat wrapping around changing content, and it is active.
WebSlices will mainstream web-site alerts where RSS has struggled.