How do you know what’s being searched for a different times of the year, or in past years?
http://www.google.com/insights/search/
How do you know what digital products are selling?
How can you tell how many affiliates are promoting a product?
How do you see how much digital products are selling for?
http://www.clickbank.com/advancedMarketplaceSearch.htm
How much should I sell my site for?
What are other websites selling for?
How fast do websites sell?
What should I look for in a website I want to buy?
Where could I go to get a website to flip?
How can you see another websites traffic and detailed statistics?
http://flippa.com/
How can I tell what products are selling?
How can I find top sellers?
Where can I see trends of items being sold?
How can I see what products are hot?
http://www.terapeak.com/features/
Where can I find entrepreneurial ideas?
Where can I find new inventions?
http://feeds.feedburner.com/springwise/
How can I tell what people are searching for on Google?
What keywords are people using to search for something?
What keywords do people use when they buy?
What keywords do people use when they’re looking for free information?
https://adwords.google.com/select/KeywordToolExternal
How can I get an idea of how much traffic a website gets?
How do I get demographic data for a certain website?
How can I tell how much income visitors have?
How can I tell which users are mail or female?
http://www.quantcast.com/
http://www.alexa.com/
http://compete.com/
How can I tell what adwords ads are more likely to be profitable?
How do you find profitable ads?
How can I tell how much someone is spending on PPC?
http://spyfu.com/
http://www.keywordspy.com/
Know more places for conducting market research? You can simply post a comment below!