tunnels are included with an paid lsmod.de account.
We use primarily openVPN, but could also set up vtun or tinc
Once set up, you can get IPs routed through your tunnel and thus make your subnet accessible from lsmod directly within a fixed private IP range.
Port forwardings possible.
Static IPv6 and IPv4 addresses can be routed through these tunnels.
It is even possible to join LANs at ethernet level as if there was a switch between them and play LAN games (IPX, UDP/IP, IP/TCP/IP, ...) with friends over the internet.
We tested with ADSL, linux routers and brctl (total ping round trip time 150ms).
Working configs are available - ask us.