Google just announced an interesting update to Google Reader. Google's online feed reader now allows you to track changes on any page - even those that don't feature an RSS feed. Google will create its own custom feeds for these sites and update the feed whenever it notices a change. Google Reader will display a short snippet of the page changes in the RSS feed. Until today, Google Reader would simply respond with an error message if you tried to subscribe to a site that didn't offer an RSS feed. Now, Google will simply create a new feed for the site and track updates. It's not clear how often Google plans to ping these sites, however. Thanks to this, you can easily track the latest discounts on Macys.com or updates to Zillow.com's homepage. As far as we were able to see, Google Reader creates very clean RSS feeds for these items. While Google doesn't make it obvious, you can find the newly created feed by clicking "show details" in Google Reader. Thanks to this, you can subscribe to this new feed in any feed reader and not just in Google Reader.