Type in one or more words, separated by commas. Google Trends will display line graphs showing the number of searches on those words over the past five months, along with other interesting graphs and statistics.

For example, type: math|maths, coffee (the vertical bar acts like "or"). The data and graphs show that overall more people are searching for maths than for coffee. But not in Washington DC.

Lots of good fun and good maths to be had here.

http://google.com/trends