For years, the SixXS project has been providing tunneling services for IPv6 internet access. SixXS will be shutting down in June '17 (cache).
SixXS will be sunset in H1 2017. All services will be turned down on 2017-06-06, after which the SixXS project will be retired. Users will no longer be able to use their IPv6 tunnels or subnets after this date, and are required to obtain IPv6 connectivity elsewhere, primarily with their Internet service provider.