If you have not been to LinkedIn Answers, you should check it out – it has a great section on product management. There is a wealth of information there on market research, pricing, product positioning and a ton of other stuff. Have a question? post it there for free and get answers from LinkedIn members from all over the world. Even just reading the answers to the posted questions will give you a lot of food for thought. I use it as a great resource of reading material and also answer questions. By answering questions, you are also building your brand as a product manager !
Software Product Manager by Gopal Shenoy 
Depending on the mood of the contributors i.e. the way a question is written, the activities can draw reactions from a wide range of participants.
Gopal, readers should take advantage of the opportunity. LinkedIn could use more “Product” centric questions.
You can also subscribe to the questions using RSS.