Not many people know about Google Insight. Google Insight is a web based data mining tool from Google that analyze the search patterns across specific regions and time frame. We are always subjecting Google with different search queries, Google use these search queries to analyze trends of those searches across different dimensions.
Consider the phrase "Data Warehousing". Many people are searching this term in Google for so many years, so many times. Google can use that data to plot the trends like "Popularity" of this phrase over time. Check it below,
I believe this is a nice little data mining tool from Google that can be utilized free of cost to understand the mining patterns.