Free Tools for Monitoring Hot Online Trends

Search Engines

• Google Hot Searches (also a list on the Google Trends home page)
• Google Insights for Search: “Rising searches” for last 7 days
• (also check the rising searches for specific terms)
• Google News (left sidebar: see Top Stories; click on category names or more)
• Yahoo! Search Clues
• Yahoo Buzz Index
• Bing Top Image Searches
• (click on an image to see top search queries associated with it)
• AOL Search Trends

Blog Search

• IceRocket: Popular (left sidebar)

Real-time / Social Search

• Bing Social: Trending Topics
• Social Mention: Trends
• Addict-o-matic: Hot Topics
• 48ers – Trending Topics
• Sency (filter by 32 major cities)
• Social Buzz – Trending Now

Twitter

• Twitter home page (left sidebar; can refine by location)
• Twitter Search: Trending Topics
• Topsy (home page and Trending page)
• What the Trend
• Twitscoop: Hot Trends (click on link in top navigation)
• TweetMeme
• Trendsmap (real-time local Twitter trends)
• Twittorati

Facebook

• FacePINCH: Facebook Trends
• Like Button (view popular content in multiple categories)

Google+

• Google+ (Trending Now module on home page when signed in)
• Topsy: Google+ Trending
• Google+ Social Statistics: Most Popular Posts/a> (currently broken?)

Other Social Media

• YouTube Trends
• Digg (click on Popular tab for most-shared stories in the last 18 hours)
• Reddit: Top Scoring Links Today (other time intervals possible)
• POPURLs

Source: http://www.adamsherk.com/seo/search-trend-tracking-tools/