Enabling IPv6 on your PC is not as difficult as you think. This is a quick Teredo/Miredo Howto for the most popular operating systems allowing you to penetrate most NATs and Firewalls and most likely allowing you to bypass any blocking or censorship happening at your place. As a free bonus, i will will show you where to access tons of Usenet posts, including binaries over ipv6 for free.
Nota bene: Since Teredo also works from China, you can use it together with the *.sixxs.org proxy to read any of your favourite, blocked sites.

I also have a tutorial for IPv6 with tunnelbroker.net from HE for Mac OS X.

Windows XP
WARNING: Whatever you do, make sure you have all the latest security patches for remote exploits and your Windows firewall is up, if you use 3rd party, ensure it supports IPv6. Enabling IPv6 will put you on the net, losing any protection you may have had behind your router's NAT. At the moment there are not many attacks over ipv6, but this may change any time.

Install
Open the Terminal with Start -> Run -> cmd

netsh interface ipv6 install
netsh interface ipv6 set teredo client

Wait for few moments.

Uninstall

netsh interface ipv6 uninstall

Windows Vista
Install
IPV6 and Teredo is enabled per default. You can get into the settings by going into the preferences for an network interface. "Obtain an IPv6 address automatically" should do the trick. However, Teredo will disable itself if you have "edge traversal" or outgoing udp packets blocked in your firewall or if your router is a symmetric-nat router (e.g. Speedtouch 780). In that case you have to use a tunnel broker, see comments below.
If you can go to http://www.ipv6.sixxs.net/, everything works well, if not... well, good luck. I never really got Teredo to work on Vista Business reliably, sometimes it works, most of the time it does not.

Uninstall
Add this registry value ("DWORD") set to 0xFF (long line, double-click, and copy):

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters\DisabledComponents

Or save the two lines in a .reg file and double-click it:

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters]
"DisabledComponents"=dword:000000ff


You can also go to the interface properties of an network interface and deselect the IPv6 protocol for that interface. To enable IPv6 again, replace dword:000000ff above with dword:00000000.

Debian, Ubuntu
Install
On Ubuntu IPv6 is enabled per default, but not configured.

sudo apt-get install miredo

Because the default server did not work for me, I had to change it to another one:

sudo vi /etc/miredo.conf
ServerAddress teredo.ipv6.microsoft.com
sudo /etc/init.d/miredo restart

Uninstall

sudo apt-get remove miredo

Fedora, Redhat
Install
About the same as on Ubuntu. On Fedora Core 6 & 7 IPv6 is enabled per default, but not configured. You need to get miredo rpm from the Dries RPM repository.

sudo rpm -Uvh miredo-*.rpm

Uninstall

sudo rpm -e miredo

Mac OS X
Install
Get the Miredo installer from Miredo-Osx, and install it. If you are lucky, that's it. if not, try changing the server, see Debian howto above.

Uninstall
If you want to uninstall, execute the uninstall-miredo.command script, located in the /Applications/Utilities folder.

Checking if everything is working

On the terminal type:

ping6 pugio.net

In browser come back to this page, there should be a pin-up girl in lower right corner telling you that you have IPv6 and give you some more info if you click her... If you can ping6 but can't visit ipv6 websites, check your Firefox network.dns.disableIPv6 setting, did you set it to true previously?

Cool stuff

• Getting details about your IPv6 connection
• Accessing blocked, censored Websites or just for fun:

  http://en.wikipedia.org.sixxs.org/
  http://slashdot.org.sixxs.org/

  (You can access any Website over ipv6 by appending .sixxs.org to the domain)
• "Cool stuff" to do with IPv6 I like the part about Usenet over IPv6