I thought I was one of the first to notice Google Trends today but it turns out SeoBook beat me to the punch.

It operates similar to the Google keyword research tool, but offers trends that goes back for years, and even overlaps news related to keyword search spikes, like Google Finance does. Many of the links they provide are to cheesy press releases, so that might present another marketing opportunity.

The tool also shows top cities, regions, and languages that queries occurred in. They also allow you to set timeframes and the market location.
It also allows you to compare phrases.

I compared Trend’s results with AdCenter for "country house plans" and found little overlap and I still like AdCenter better for GeoTargeting; I’m sure I can get to like Trends as well.