One of the large businesses that we worked with had an issue that's really common throughout most national businesses. As marketers, we tend to focus on our business as if there were no geographic boundaries or changes over time – but the reality is both have an enormous impact. If you can write content on topics that take advantage of seasonality, overall trends, and geography, the content can perform better.
Google has just launched Shopping Insights where you can analyze search volume over time and by geographic density. As an example, here's an example of shopping searches for tablet across the US:
You can also get granular with your research, geographically, down to a finite level. This could be extremely helpful with your advertising expenditures and personalization of your ads.
And of course, they also provide top trending searches by month and year that you can browse through.