Check out the Google trends website: http://www.google.com/trends It gives a comparitive and relative view of the trends in search engine query volume.
Ahh Google Trends, i'm not going to give a step by step guide but by using a combination of Google Trends, Blog Search and regular SERP's you can get thousands of visitors within hours of making a post. Pillage the QDF algo i say. Google Trends does exactly what it says, provides current trends of what people are searching for in almost real time. Basically what's hot on the internet, anything from a bomb blast to American Idol searches after the show.