Reddit is a social bookmarking site that allows you to what users are bookmarking and content gets ranked by what users consider to be “good” and what they consider to be “junk”. Although it may not give you a true picture of popular trends like a keyword tool could give you, it is a very popular website and can give you indication of the types of content users are interested in.
You can browse by category. At first, the categories might be hard to see, but they’re crammed at the top of the page:
You can browse by “what’s hot”, “new”, “controversial”, and “top.”
You can also use the search box in the top right corner:
You can then sort your results by relevance, how new the content is and how popular: