Ask HN: How do you preform competitior monitoring and where do you get the data?

I am developing a competition monitoring web application and just wanted to ask the community how do you currently stay updated with your competitors activity online and where do you find useful information about them? I am trying to join several information sources under one big roof in order to get the daily competitor activity stream for a nice MVP. What I would like to ask is whether anyone finds this idea worth trying or has any other suggestions about the concept? Also I would really appreciate if you can give some comments about my pre-launch page that I use to collect future clients emails (http://kompetoo.com/signup/).