Yahoo Clues: New Fun Search Keyword Tool
What is it?
On November 16th, 2010 yahoo announced a new tool named Yahoo Clues. Yahoo clues basically gives you insight into the types of people searching for specific keyword phrases and shows related terms based on those searches and searchers.

How does it work?
The tool allows you to plug in one or two keyword phrases and it them plots the search trends of those keywords on the page. It shows you keywords popularity over time, searches by age and gender, income level, geographic location, search flow and related searches.
For example, lets compare the queries for Iphone and Android Below.

Search flow basically shows you most probable previous and next user searches from an analysis of aggregated search patterns:

For more definition on these graphs and data points, watch the video blow

Source : http://www.searchenginepeople.com