On this topic we've just launched a hosted competitor monitoring service, <a href="http://www.webalertpro.com" rel="nofollow">http://www.webalertpro.com</a><p>It's a website content monitoring service that generates daily reports for all content changes for all your competitors websites.<p>It was a quite an interesting technical challenge since most sites generate loads of small unimportant changes (and text moving around in lists, dynamic news reels, dates etc..) of no interest to anyone. So the approach we tool was to rank each change. So when a user adds a new site to monitor the first few days of crawling it are spent learning where the important content changes take place on the site. We can then report assign to each change alert a score between 1 and 10 (ChangeRank!).<p>We're getting quite some interest in the applications of this, from campaign monitoring, marketing compliance and figuring out what content changes your competitors are making for the purpose of SEO.