HDL pre-synthesis tools which check code for synthesizability. Then suggest replacement code where problems are found.
http://www.sandstrom.org/about.htm
Develops semiconductor intellectual property and system level IC products for LAN, WAN and Broadband applications utilising proprietary mixed signal and digital signal processing (DSP) technologies. Includes product specifications, application notes and company news.
http://www.softmixedsignal.com/
Verilog tutorial, Digital Electronics tutorial. With Sample questions asked in Interviews. Links to free tools and books. Examples.
http://www.deeps.org/
Development of VHDL & Verilog modules (IP) (DES, UART, ANSI X9.52,..)
http://www.tetraedre.com
Specialize in full turn-key, customer facility training programs in VHDL, Verilog,C++ modeling, formal verification, and FPGA design.
http://www.exsultation.com/
What is Verilog? A Brief History of Verilog. Tutorial. Verilog design tips.
http://www.doulos.com/knowhow/verilog_designers_guide/
Frequently Asked Questions And Answers.
http://vhdl.org/comp.lang.vhdl/
from Intrinsix-VHDL Technology Group.
http://www.vhdl.com/