What’s HOT in search? 搜索引擎类：
- Google hottest trends (updates throughout the day);
- Yahoo buzz allows to see the daily buzz score (=”the percentage of Yahoo! users searching for that subject multiplied by a constant to make the number easier to read“) and the move (i.e. how fast this has become popular):
- Top Ask.com searches: most searched at Ask.com past week;
- Aol.com hot searches;
- Daily MSN A-list;
What’s HOT around social media? 社会化媒体类：
- Delicious hot tags;
- StumbleUpon popular tags (recently popular and all the time);
- Popular Flickr tags (in the last 24 hours, over last week and overall);
- Twitter hot topics: Twitscoop - lists most popular terms discussed at Twitter and displays the trend history in the form of a graph:
What’s HOT in blogosphere? 博客圈：
- Technorati Popular: top searches and top blogs (in the last 48 hours);
- BlogPulse key phrases allow for “trend this” option that graphically represents the trend history:
What’s HOT in eCommerce? 电子商务：
- Amazon tag cloud = which tags Amazon customers use to classify products;
- EBay pulse = popular eBay searches.
What’s HOT everywhere? 综合：
- SEOmoz popular searches aggregate data from most sources mentioned above (Google trends, Yahoo buzz, Technorati, etc).