A new tool called Google Correlate lets you input a search term and then creates a state-by-state map of how many people search for it. It then it shows you what other search terms have similar state-by-state patterns.
A search for my name (what else would I have plugged in first?) shows the most searches coming from my home state of Oregon, and a notable lack of interest stemming from the Great Plains. Of note: interest in McBain: The Movie follows a very similar regional pattern:
I’m trying to think of a good scientific use for this tool, but I keep getting stuck on the fact that the top regional correlate of personality is “nipple stimulation.”
The Hardest Science 
I work in HIV epidemic prediction using mathematical modelling, and one of the things we use heavily is behavioral data. Search terms might hold valuable insight into how the epidemic is progressing, in a similar way to how Google Flu trends works. However this is currently for the US and we are in Australia, so our work is based on Australia and south east Asia. If google wants to been at the cutting edge of these developments, it really needs to open up a lot more and allow us to download more data :)
Another problem is that you type in the search term and google finds the highest correlated terms that match. But that might not be what you are after. That and the most correlated terms are usually misspellings of the terms you are looking for. I wrote a post about this on my blog which links to a page that forces Google Correlate to compare the terms you are after.
http://jamesjansson.com/blog/2011/05/31/christmas-causes-colon-cancer-google-correlate/
I agree – I cannot see why I would use Google Correlate over Google Insights for Search. Even inputting my own data does not provide particularly lucid results. In fact, I agree with James above that it is useful for tracking what people are searching for around epidemics/disasters etc – that’s ultimately how the tool came about from tracking flu epidemics. However, this is after-the-event and so marketers cannot take advantage of this – telling a shelter agency to bid on certain keywords around a disaster 2 weeks later via Correlate is not going to help that shelter agency get aid where it’s needed. I think the tool needs to evolve to be track more real-time trends.