UltraSurf is a very small program (less than 500kb) that will automatically change your Internet Explorer's setting to make use of anonymous proxy server in the United States. It is free. It also has add-on for Firefox browser.
It can be used to hide/obfuscate your computer's location, and be a workaround to overcome possible web censorship and blockage.
Any website you connected with your web browser is able to trace your computer's IP address, and use it to find out your location. What UltraSurf do is to connect your computer to their server, and then connect to the destination website with the IP address of their server instead of yours.
This will make any websites you surf on or browse into, to trace that you are coming from United States instead of your actual location.
You can see how the IP address is traced by visiting to http://whatismyipaddress.com/. See what's the different before and after you run UltraSurf.
UltraSurf also has options to allow you to remove your trace in your computer (what webpages you have visited) by deleting the cookie and history information automatically the moment you exit the program.
Click here to find out more about UltraSurf and to download it.