There are many things you can do to a Google URL to modify the results of a search. However, two that are almost indispensable are pws and gl.
First off some URL basics. URL's such as http://www.seedkeywords.com/ can be modiefied to pass information around. A simple example would be:
In this example when the page is loaded the parameter id with a value of 1 is passed to any script used to generate or manipulate the page. This is very useful for coders.
If you go to Google and do a search you'll notice the URL looks very complicated, possibly something like this.
If you look closely you'll see q=blue+widgets in amongst the other gobbledegook, that's the search term I typed in. These are known as query string parameter value pairs or URL parameters.
Now before you start glazing over and think this is one for the geeks stop! Editing these URL parameters is easy and there's a good reason to know how to do it, well two anyway.
If you add &pws=0 to the end of the URL above you will get rid of any personalisation in the results. Personalisation is Google trying to help you find things relevant to you when searching which is nice but a PITA when doing research. Although you can turn web history off I've found this doesn't eliminate personalised results, this trick does.
The second tip is to add &gl=country code to the end of the URL such as &gl=GB for Britain or &gl=US for the States. This shows country specific results.
In case you are wondering the & simply separates one parameter/value pair from another - geeks, don't you love 'em.
Using the two tips above you can view 100% non personalised results and choose which country specific results to see, all pretty useful stuff when researching your SEO efforts.
If you'd like a more complete list of stuff you can do with query strings you might find this quite useful.