RFC 2292: Advanced Sockets API for IPv6
Defines some the advanced features of the sockets API that are required for applications to take advantage of additional features of IPv6.

sockaddr.com
Programming Resources for WinSock 1.1 and 2 including sample programs, specifications, and links. (Lewis Napper)

TCP/IP Raw Sockets
MSDN documentation about Raw Socket specification. Raw sockets can be used to create your own protocols.

Windows Sockets 2
Developer documentation of Winsock for all Windows platforms.

Windows Sockets Programming
Links to get started with WinSock programming. (Ed Snible)

WinSock Development Information
Sample programs, technical articles, links, and an extensive WinSock error reference. (Bob Quinn)