Before all of the other "old fogies" get uppity and start talking about how you need to be doing your school work and not trying to get on myspace while at school, I want them to think back about how many times they passed notes, doodled, or talked during class. I know that I did. This is the same thing. It just has a tech twist to it. Kids will screw off in class any chance they get. It's school.
Just make sure you get your classwork done as well.
That being said, you obviously know that it's going to be difficult to get around any filters that your school's IT guys have put into place. As soon as a new proxy site is spotted, it's usually blocked. Good luck getting around them because believe it or not, those IT guys know their stuff and they are paid well for it.
Anyhow, here's a list of all the proxies that I've seen so far. Good luck as your IT guys is probably reading this list right now as well and blocking them. He gets the internet too and knows this is where tons of folks come to get proxy sites.
Proxy sites(the newest are at the top of the list):
http://boxofproxy.com
http://offcampuslunch.com
http://searchandstudy.com
http://abc.searchandstudy.com
http://free.offcampuslunch.com
http://myspace-anonymous-proxy.xtreview.com/cgi-bin/proxy.pl
http://www.kproxy.com
http://www.proxypimp.com
http://www.isneakin.com
http://www.ixune.com
http://www.myhighschoolproxy.com
http://www.schoolboredom.com
http://www.proxytoplists.blogspot.com/
http://www.iblocked.com
http://www.proxydom.com
http://www.ninjaproxy.com
http://www.surfiner.net
http://www.vpntunnel.net
http://www.xroxy.com/
http://www.phproxy.org/
http://www.howtounblockmyspace.com
http://www.hidemyass.com/
http://www.sneakysurf.com/
http://www.sneakrascal.com/