Hacker News Reader

The data actually already exists for this. The Wayback Machine stores caches of website data, you could do simple checks for changes, and then report back any significant differences. Possible statistical site could be built to show the highest-moving sites based on the changes to their content.

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The Wayback machine isn't close to real-time.

i've used http://page2rss.com/ with some success. no signup required.

There are a few things to do this, I personally have used Feedwhip a bunch. The guy who writes it is really nice and they have both email and RSS options. http://www.feedwhip.com/

I blogged about it some time last year http://kid666.com/2007/05/29/oh-whip-me-baby-feed-me-feedwhi...

http://liltompeep.com does just that with no sign-up whatsoever.

http://www.rsspect.com/

Not cumbersome at all.

try http://www.feedbeater.com. No signup, just enter the url and get an RSS feed showing the actual content that changed, not just some list of links.