Google has rolled out a new feature which shows what is or was trending any given month back to 2004. Currently the feature is limited to the US but it is expected to be expanded to encompass other countries soon.  The new feature, called "Top Charts," is similar to Google's yearly Zeitgeist, but instead of showing the top trends over a period of a year, "Top Charts" is updated monthly to show the most searched-for items in each of the included categories.