If you are using Chrome or Firefox I strongly recommend you install the addon/extension called Media Hint. Once installed there are no configuration changes to be made, as the extension will automatically change proxy according to the website that you visit.
Alternatively I have had alot of success with the application Spotflux:
Alternatively if you are prepared to pay then I would recommend Identity Cloaker They offer a free demo it's fully functional and there is no time restriction on how long you can evaluate the software. However, when the demo mode is enabled, it is possible to visit just a few domains/websites.