ABEL Primer - Overview of the ABEL Hardware Description Language. - http://www.ee.upenn.edu/rca/software/abel/abel.primer.html
Titivillus: Software Development - Links to many programming languages, including several HDLs. - http://tos.maintree.com/titivillus/softwaredev.asp
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/
HDL at Wikipedia - Definitions, resources, and links related to hardware description languages. - http://en.wikipedia.org/wiki/Hardware_description_language
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/
Digital Core Design - VHDL, Verilog synthesizable and simulation models. - http://www.dcd.pl/