There is a publicly available IPv6 to IPv4 web proxy from Sixxs.org. You can reach any IPv4 site (that is, any web server) over IPv6 with this proxy.
Just append .sixxs.org after the host name and you can reach the site via IPv6. They proxy is also kind enough to rewrite any links in the HTML document so that you stay on the proxy even if you click on link.
For example to reach the IPv4 only site www.cnn.com via www.cnn.com.sixxs.org.
Of course, IPv6 must be implemented on your client first.