At product owner level, wherein I am sole owner of product / portfolio or LOB, I ensure that I have maximum possible coverage of reference points, inputs from which can be translated into requirements and placed in backlog.
Taking care of large number of reference points is cumbersome, especially if you are dealing with a cloud based delivery platform that enables high quality services to large number of users. Also, you may not like to wake with a news that your competitor has announced a technology road map that will beat your next release on its launch date, I mean something like dead on arrival. Therefore its imperative for a product owner (or product manager is some cases) to devise a radar that ensures that no such surprises ever enters its space and take him by surprise. I would like to share technical specs of the radar the I have devised to ensure that I have maximum coverage of my space.
Technology: CTO, Architecture group, research group, engineering & individual contributors - consider their inputs from time to time, understand how technology is evolving as it possess the enormous power to disturb the current market equations. Ensure you collect & track key forums, bodies in govern technology in your space.
Competition: If you have not set news alerts of your competitors then I doubt you as product manager. Public announcements of your competition must reach you as it get out (don't set daily or weekly alert, but as it happens). While this a sure must, try and develop channels / contacts via partners, VARs who can provide you with any key movement on competition front. For example: a closed door beta program initiated etc
Sales: They are fast, relatively unreliable but holds a bold spot in your ecosystem. Talk with them regularly. It will requires some real efforts from you to get the true information out from them, why not go out with them for a drink on a Friday evening - trust me they cannot hold on to any information.
Customer support: Yes you heard it right. They shout only when they cannot tolerate the pain, but as matter of fact, they are always in pain. Try and get daily or weekly reports on kind of escalations they have been dealing with. Be-ahead of them and take their feedback constructively.
User usage data: Usage data helps in providing deep insights on what's working, what's not and what's desired. A good product manager will never undermine the importance of usage data. Getting usage data may be easy but how to use it and what to derive from it will test you truly. Data is raw material and information derived from data is the true weapon.
Customers: Meet them regularly, you will get to know the mood of the market and movement of the market place. customers or/ and user community place is temple for a product manager. Visit and pray regularly to get rich fruits.
Analysts & Marketing: Believe it or not it matters. read published reports on market, product & technology published by leading research houses. Get hold of market size, share, vertical information, new players, M&A etc. this helps you understand positioning requirements, gaps in your offerings & potential of feature & vertical.
Competing & Complementing industries: Keep an eye, occasionally if not regularly. Any major movement in this space will impact your plan sooner or latter.
Rules & Regulations: do I need to say anything about this? R&R governs your industry and its part of your core duty to keep track of newer guidelines, emerging standards and newer concepts that are being released or are discussed. At times a single change in rule can impact your release strategy for a specific geography or for a specific feature or entirely.
Social Media: Keep an eye on key people in competition and on key competition on Linkedin, Tweeter, FB, Quora etc... who has moved out and moved in, which company has shifted its gear, are there too many people moving out or in of your competitor....
I guess that's quite a lot for a individual but you can always take help of technology and peer group to structure this better. Let me know what you think of my radar and also do share details on how you ensure no alien enters your space.