This limitation is quite annoying for testing out IPv6 on your(s) server(s) while enabling IPv6 is at least as important as on any other computer.
Besides ping6, traceroute6 or other basic network tools, there is a way to effectively test IPv6 on a remote computer/server with SSH access enabled. Simply use a socks proxy, by using this command on your personal computer (not the server!):
$ ssh -ND 1080 login@server -N Do not execute a remote command. -D Specifies a local “dynamic” application-level port forwarding.
No remote shell session will be open since only traffic forwarding is required here. Now, edit your browser’s proxy settings and activate SOCKS 5 with host localhost port 1080. Go to test-ipv6.com and ipv6-test.com, you should see test results concerning the remote computer/server!
If you are only interested in your IPv4/IPv6 address, lv0.in/ip/ provides this information a clean fashion.
Oh and by the way: <3 IPv6