I can't recall now, the other ways I was going to suggest to get around filters... but here's a writeup that gives a few helpful pointers:
http://www.boingboing.net/censorroute.html
so yeah, the easiest thing you can try is
https://vtunnel.com
...otherwise if you want to do it the über geeky, and mostly infallible way you can do this:
you'll need: a broadband internet connection, a computer that's always on, the ability to access the browser at school's options menu, and the ability to run small programs on the school's computer. (some places go all out and block the ability to run programs, which is a whole other story)
At home, you'll need to be running a SSH server.. this basically provides a fancy encrypted way of logging into a computer over the internet. If you're running a unix-based at home system such as linux, mac osx, freebsd, etc, you may already be running one.. otherwise you can type sshd to start it and add it to /etc/rc.d to have it start automatically.
If you're running a Windows computer you'll need to either install cygwin and then install the linux version of sshd, which I won't cover here, or you can download a number of different windows programs that do it.
http://www.bitvise.com/winsshd.html is one such program. (though iirc it only gives you a 30 day trial period)
Now, once you have a SSH server running at home, you need to connect to it from school. If you're running a unix based system at work/school/china, you probably have everything installed for this already, but I'm not going to go into that. If you're running a windows based system you can run a small program called PuTTY to connect to your home computer. It doesn't need to be installed, and can be run off a floppy disk, usb flash drive, ipod, or by emailing it to yourself.
Run PuTTY, put your home computer's IP address
[sup]*[/sup] into the IP address box.. on the left, click SSH, Tunnels, then under "Add Forwarded Ports" type a number and click the "Dynamic" checkbox. Click Add. Click Open. a box will eventually pop up asking for your username and password, type those of your home computer.
Now, go into your web browser's options menu and find something to do with advanced connection settings.. there should be a setting in there for "connect through a proxy server" select "SOCKS". for the proxy server address type "localhost", and for the port, type the number that you typed into putty's port screen. (in firefox this is: Tools, Options, Advanced, Network, Settings, Then "Manual Proxy Configuration" then type "localhost" and port into where it says "SOCKS")
TA-DA you can now browse the internet just like you could at home... in fact, you ARE browsing the internet from home.
not working? are you on wireless, or otherwise have a router at your house? check out
http://portforward.com for information on how to set up your router to allow this.
If your school's browser is configured to not give you the option to get into the preferences screen, PM me, there's bound to be a way around that.
* - if you don't know your home IP address, check out
http://whatismyip.com (while browsing from home)
Now there is nothing that surprises me on the internet, it's like 'whatever, another shock site... I'm off to watch TV...'. 
