Ask HN: Would you use a good RSS rewinder?

I needed something that could replay blogs from the beginning. I thought of doing it quick and dirty, that is parse the HTML of the blogs I want to replay by hand.

But then I realized that there is a more general problem about blogs, podcasts, etc. to be solved; that is how do you make a machine understand the chronology of the posts, file them by categories, tags, etc.? The HTML structure is different for every blog, so I could build a general-purpose web service which would turn any blog into an xml file ready for consumption by a machine.

Right now I don't see good uses for it apart from RSS replay but let me know if you are interested/have ideas about this.

By the way I plan on implementing this using something similar to Opera's fast forward button and then walking up the posts. Shouldn't be too difficult.