I'm actually suprised that many people never heard of Google Alerts. I'm using this Google feature for a couple of weeks now and, for me, it's very useful!
I have used a lot of other programs in the past, such as Copernic Search, which uses several different searchengines, but Google is still my fav searchengine since others don't display as many results. So that's why I switched to Google Alerts instead. No more programs to install since it's an "online tool".
For the Google Alerts, you just have to enter your search term and create an alert for it. It then notifies you by e-mail with the new results.
It offers six types of alert searches: "News", "Blogs", "Web", "Comprehensive", "Video" and "Groups".
You can also specify if you want the email with the results "Daily", "Weekly" or "As it happens". The "As it happens" doesn't work - although, not for me. That's why I've set it to daily.
A nice extra feature would be a "website watcher" included in Google Alerts (this for pages that don't provide Atom or RSS feeds) - where you have to enter the URL of a website, specify a filter (what changes to ignore) and Google notifies you of the changes being made on that page since your last visit. I already use another program for that, but it would be nice if this feature is also included in Google Alerts.