GNU AWK original documentation is contained in the distribution at ftp://ftp.gnu.org/pub/gnu/ and a browsable copy is available at http://home.t-online.de/home/Juergen.Kahrs/inet_toc.html.
The Cygwin tool set, the UNIX environment on top of Windows 95, resides at http://sourceware.cygnus.com/cygwin/.
BSD Sockets are a popular API for networking; a good introduction written by Ivan Griffin and John Nelson can be found in LJ, February 1998.
Perl has the socket API and many modules at http://www.gmd.de/CPAN/README.html.
netcat is available for UNIX and Windows 95 at http://www.l0pht.com/~weld/netcat/.
Portals are available in BSD UNIX systems and described by Richard Stevens at http://www.kohala.com/~rstevens/portals.ps.
/dev/tcp is available in ksh93 and described at http://www.kornshell.com/.
Ralph Becket has some useful scripts at http://www.cam.sri.com/people/becket/awk/awk.html.
Anthony Mitchell has a list of Internet-accessible machines at http://www.mitchell.net/ant/machines.htm.
Yahoo also has a list of devices connected to the Internet at http://www.yahoo.com/Computers_and_Internet/Internet/Entertainment/ Interesting_Devices_Connected_to_the_Net/.