Viewing US ads & results in Google

Today I was doing some research and wanted to know how to view Google ads (via Adwords) that were focused at the US market. Typically, if you do a search for a keyword in the UK, Google sees you are from the UK and shows you ads from UK companies. I found the method thanks to this post. If you want to see ads that would be shown to people in the US, you just need to add &gl=US to the URL after you've done your search, for example http://www.google.com/search?hl=en&gl=US&q=geoffblog