Help with proxy servers to get around blocked websites

Tweet

Here's my dilemna. I'm using a shared internet connection and I do not have administrator rights to block or allow specific websites. I'm fairly sure now that it's not the ISP that is actually blocking the site. I know many of you access the internet through work or have bypassed ISP restrictions in certain countries (getting around the Myspace block is one that comes to mind). What software/program was the most reliable without sacrificing too much speed? Or is there a certain website you could recommend that might be helpful to me? Any help or suggestions would be appreciated, thanks :)