Dan Gillmor’s blog has a pointer to Google Alert, a web tracking system. Its a nice idea: you give them a search string, which they submit to Google each day on you behalf. You get an email every time the result of the search changes. Or you can get the results by RSS.
Without trying this, its hard to know how well it works. badly crafted search strings would probably generate too many false alerts, so I don’t know how careful you’d have to be. Also, whats the business model? Ads? If I get time, I’ll try it.