IRC servers for various networks

Undernet:
eu.undernet.org
us.undernet.org

EFnet:
irc.efnet.net
irc.he.net
irc.nac.net

EFnet IPv6:
efnet.ipv6.xs4all.nl
irc.ipv6.homelien.no

IRCnet:
irc.freenet.de
ircnet.choopa.net

IRCnet IPv6:
irc.ipv6.cesnet.cz
irc6.ngnet.it

Freenode:
vinge.freenode.net
tolkien.freenode.net