Want to find out who is talking about what in your niche or industry? There are many search engines that allow you to search one or multiple sources of information to see real time results. Check out these popular (and free) blog, forum, and social media search engines.
Blogs
1. Technorati
Technorati lets you search blogs and posts by topic using the search bar. You can see the latest posts in particular subjects by clicking on them in the menu. They also have a tag page where you can choose a particular keyword and see commonly mentioned topics
2. PostRank
PostRank allows you to search for blogs on particular topics, as well as see the top blogs in each category based on reader engagement through comments and social sharing.