what are good proxy sites for school computers?

[Rich C]

If you have always-on internet at home, you could set up your computer at home as a proxy server and write down the ip address (go to http://www.whatismyip.com) and at school enter it into the school web browser's list of proxy servers. If you dont know, in order to get to that in firefox you go to: Tools>Options>[Tab]Advanced>[Button]Settings>[ComboBox]Manual Proxy Configuration>[Type IP address from home in first box by 'manual proxy configuration']

http://www.linquist.net/geek/proxy

After completing those steps, you should be set to browse using your home PC as a proxy.

Otherwise, you could go to http://www.logmein.com and create an account, add your home computer onto the computer list (install logmein software for it to work), then when you go to school go to logmein.com and choose to use your home pc remotely. it will ask you to install the logmein plugin to the browser, do it, and you can use your computer at home on your school's web browser.
*note: for logmein to work while you're at school, you need to make sure the computer is running while you're trying to access it at school!