Another list of IPv6 Internet Exchanges can be found here: IPv6 status of IXPs in Europe
TIX (tallinn interneti exchange with ipv6 support)
Euro6IX, European IPv6 Internet Exchange Backbone
French National Internet Exchange IPv6 (since 1.11.2002 active). FNIX6 provides a free and reliable high speed FastEthernet interconnection between ISP located in TeleCity Paris.
INXS: (Cable & Wireless) Munich and Hamburg
AMS-IX: Amsterdam Internet Exchange
Tunnelbroker AS8758, Dolphins Network Systems (since 20.12.2002 online)
ESnet, USA - Energy Sciences Network: Tunnel Registry & Address Delegation for directly connected ESnet sites and ESnet collaborators.
Hurricane Electric, US backbone; Hurrican Electric Tunnelbroker (also available under http://tunnelbroker.com/) Press Release: Hurricane Electric Upgrades IPv6 Tunnel Broker Tunnel Broker Endpoint Autoupdate, Perl Script
http://tunnel-broker.singnet.com.sg/, with NAT and IPsec option
Public 6to4 relay routers (MS IIE boycott!)
Note: These services are mostly only available with a valid IPv6 connection!
Quake2 over IPv6
Something missing? Suggestions are welcome!