Meta-HDLs

Hydra Computer HDL
Hydra is an HDL based on the functional programming language Haskell.
http://www.dcs.gla.ac.uk/~jtod/Hydra/

JHDL
JHDL is a method of describing (programmatically, in JAVA) the components and connections in a digital logic circuit.
http://www.jhdl.org/

MyHDL
MyHDL is a Python package for using Python as a hardware description and verification language.
http://www.jandecaluwe.com/Tools/MyHDL/Overview.html

Perlilog
As the name implies, Perilog uses a mix of Perl and Verilog to construct parametric hardware designs.
http://www.opencores.org/projects.cgi/web/perlilog/overview

RHDL
RHDL (Ruby Hardware Description Language) is an HDL based on the Ruby programming language.
http://www.aracnet.com/~ptkwt/ruby_stuff/RHDL/