A great - but often overlooked - Google tool is Google Insights (also known as Google Insights for Search).
Google Insights offers a wealth of information including search patterns across specific regions, categories, etc.
- I used the search term "college football" within the United States over the last seven days. What was hot? "ESPN college football" with high regional interest in Alabama and Georgia.
- I used the search term "digital camera" for a product search in the United States over the last 30 days. What was hot? "Digital Camera Canon". In addition, searches for "digital cameras" was up 60% over the last 30 days, while searches for "nikon digital camera" was up 50%.
- I searched by location - Cincinnati, Ohio - and targeted the keyword "pizza" to see what's been happening over the past 30 days. The top searches were "Pizza Hut" and "Marco's Pizza" with strong regional interest in Covington and West Chester.
Test Google Insights on targeted keywords; competition; trends, etc.