I used to use google alerts initially. But now I have switched to subscribing to the feeds from news.google.com and blogsearch.google.com for custom search quer

I used to use google alerts initially. But now I have switched to subscribing to the feeds from news.google.com and blogsearch.google.com for custom search queries, along with subscribing to competitors' blogs and forums. This should cover media coverage, new features and customer reactions. I do not monitor for downtimes specifically, as any major downtime will anyway come up in the news/blogs. But if you are very much interested you may sign up for website monitoring tools like site24x7.com (has a free version) or pingdom.com (no free version) and monitor their downtime too. Some of these tools check for web content changes too. You can use it to track changes made to specific pages of your competitors' website. I hope you track references to your product/service too, as you need to respond quickly to customer reactions, both positive (with at least a thanks) and negative (apologize and fix the problem).