ABEL Primer
   Overview of the ABEL Hardware Description Language.
   http://www.ee.upenn.edu/rca/software/abel/abel.primer.html

Digital Core Design
   VHDL, Verilog synthesizable and simulation models.
   http://www.dcd.pl/

Doulos KnowHow
   Designer's guides and models for VHDL and Verilog. SystemC home. Also Perl and Tcl/Tk for hardware designers resources.
   http://www.doulos.com/knowhow/

HDL at Wikipedia
   Definitions, resources, and links related to hardware description languages.
   http://en.wikipedia.org/wiki/Hardware_description_language

Ruby
   Ruby is a notation and design discipline intended for the development of regular integrated circuits and similar hardware and software architectures.
   http://web.comlab.ox.ac.uk/oucl/work/geraint.jones/ruby/

Titivillus: Software Development
   Links to many programming languages, including several HDLs.
   http://tos.maintree.com/titivillus/softwaredev.asp