Includes papers, presentations, conference publications and SAVANT VHDL, a free VHDL analyser and simulator. From University of Cincinnati.
http://www.ececs.uc.edu/~paw
VHDL synthesizable model of PIC16C5X microprocessor.
http://tech-www.informatik.uni-hamburg.de/vhdl
http://margo.student.utwente.nl/el/cad-cam/whdl025.exe
Oroboro is a testbench and modeling language that uses Python generator functions.
http://apvm.sourceforge.net/
http://www.syncad.com/ver_down.htm
a handbook describing the basics of Verilog including some history and several examples.
http://www.eg.bucknell.edu/~cs320/1995-fall/verilog-manual.html
Hydra is an HDL based on the functional programming language Haskell.
http://www.dcs.gla.ac.uk/~jtod/Hydra/
VHDL, Verilog, and IBIS models of Micron's memory products
http://www.micron.com/