D & C Electronics
D and C Electronics. World wide distributor of Electronic vacuum tubes sockets and magnetrons at the best prices. Replacement tubes for Perkin Elmer mass spectrometer
http://www.dandcelectronics.com

Golden Middle
Makes tubes amplifiers, preamplifiers, vacuum tubes components, sockets and transformers. Based in Saint-Petersburg, Russia.
http://www.goldenmiddle.com/

Tube World, Inc.
We sell the best new old stock NOS vacuum tubes, cryogenically frozen kuhl tubes, superior customer service offering only top quality tubes. Preamp tubes, power tubes, amplifier tubes, replacement tubes, resistors, inductors, transformers, power triode tubes, Western Electric tubes, audio test equipment, global shipping. Fast shipping and superior customer service! A leader in NOS vacuum tubes since 1996.
http://www.tubeworld.com/

TubeTronic
tubetronic.com
http://www.tubetronic.com/

Billington Export Ltd.
Billington Tubes and Valves. The UK's leading valve and tube Wholesaler and Retailer.
http://www.bel-tubes.co.uk/

Phamitech International Company Ltd
Exporter of electron tubes, TWT, valves, thyratrons, magnetrons, klystrons, transmitting tubes, heating tubes, vacuum interrupters and X-ray tubes made in China
http://www.phamitech.com

C++ Sockets Library
A C++ class library wrapping the berkeley sockets C API, and therefore works on most unixes and also win32. Features include, but are not limited to, SSL support, IPv6 support, TCP and UDP sockets, HTTP protocol, and highly customizable error handling. [Open Source, GPL]
http://www.alhem.net/Sockets/

TCP/IP Raw Sockets
MSDN documentation about Raw Socket specification. Raw sockets can be used to create your own protocols.
http://msdn2.microsoft.com/en-us/library/ms740548.aspx

BSD Sockets: A Quick And Dirty Primer
Crash course in programming BSD sockets
http://www.ugu.com/sui/ugu/show?I=help.doc.network.sockets&F=1111111111&G=Y

Tooltronics, Inc.
TOOLTRONICS Inc. specializes in high current Kelvin test sockets, burn-in sockets and test fixtures, focusing on but not limited to the DC-DC/Power Converter market. The company has a strong 44 year track record.
http://tooltronicsinc.com/