Google Trends

Google Trends is a tool from Google Labs that shows the most popularly searched terms from 2004-now.

Graph Trends
Many search terms may have similar graphs relating to one another. For Example: Wikipedia and Myspace both have similar graphs for the 2004-2006 range. These types of graphs could be labled under the [ Exponential] category. This will help people discover what is becoming popular and what is declining in popularity. Seasonal search terms can have there own category. Different theorys about the way the graph changes can be speculated on Wiki Theory.