You have been using Google Alerts for keeping track of anything new and interesting on the web around your topics of interest but did you know that there exists a plethoro of other email alerting services that are again very useful and do not cost a penny. Let me just dive right in.

1. Follow your World - The is a Google service that allows you to track satellite images of various locations within Google Maps and Google Earth. You’ll get an email alert each time Google releases new and updated aerial imagery for the various locations that you are tracking.
2. Newsle - The service tracks news websites and alerts you when any of your friends or people in your social network appear in news stories. It analyzes your LinkedIn and Facebook accounts to determine your friends and colleagues.
3. Brook - Your Twitter timeline is a never-ending stream of tweets and sometimes good tweets get lost in the noise. Brooks sends you a daily email digest of the five best tweets from your favorite tweeters so you’ll never miss what they say.
4. Visual Ping - You can visually mark an area on any web page and the service will send an email alert when the web page changes. You can also set the trigger to go only when there are major modification to the page.
5. Earthquake Alerts - The USGS website offers a free earthquake notification service that sends you email alerts when earthquakes are reported in your area. You can mark your area on a Google Map and it will notify you of any seismic activity around that area.
6. Domain Tools - This service allows you to monitor web domains and alerts you via email when any of the monitored domains are nearing expiration, when they are renewed or if there any crucial changes in the Whois records of the domain. Explore more tools to know everything about websites.
7. Book Alerts - You can use the search feature of Amazon to track the release of upcoming books by your favorite authors. Just enter the book publication date somewhere in the future.
8. Follow-up Gmail - The “starred” folder of your Gmail is a dumping ground of email messages that require follow-up. This Google Script sends a daily digest of 10 random messages, picked from your starred items, that may require follow-up.
9. Talkwalker - Get email alerts when your name, your brand or your website gets mentioned in news stories, websites and forums. This may be a good alternative to Google Alerts.
10. Wikipedia Watch - You can put one or more Wikpedia pages in your watchlist and the website will send you email notification when the content of these articles is edited. The changes are also available as RSS feeds.

Also see: Email Alerts for Website Downtime

14. Mention - While Google Alerts track mentions on websites, the Mention service monitors the social media websites and commenting platforms, Disqus for example, for your search terms. Also, it only monitors freshly-baked content that has been published in the past 24 hours.
15. Timehop - Every morning you’ll get an email with a photograph or a status update that you may have published on your Twitter, Instagram or Facebook account an year ago. Timehop is avilable as an app for Android and iOS devices.
16. IFTTT - The popular IFTTT service offers several email alerting services rolled into one. You can receive email alerts for severe weather conditions, get notified about stock price fluctuations, monitor Craigslist and more.
17. Amazon Price Tracker - Create a list of one or more items available on the Amazon website and you’ll get daily email alerts when the price of your monitored items goes up or down.
18. MouseLock - This is a unique service that monitors your unattended computer and send your an email alert with the picture of the person who tried to use the computer in your absence.

Also see: Most Useful Email Addresses