Digital Core Design
Synthesizable VHDL and Verilog HDL IP Cores.
http://www.dcd.pl
The Hamburg VHDL Archive
Provides a collection of free (i.e. public-domain) or shareware, VHDL documentation, models, and tools.
http://tams.informatik.uni-hamburg.de/research/vlsi/vhdl/
Micron Technology
VHDL, Verilog, and IBIS models of Micron's memory products
http://www.micron.com/
Microsystems Prototyping Laboratory VHDL Model Collection
VHDL models from Mississippi State University
http://www.erc.msstate.edu/mpl/distributions/vhdl/
Synthesizable VHDL Model of 8051
A synthesizable VHDL 8051-microcontroller model, maintained by the Dalton Project of the University of California in Riverside.
http://www.cs.ucr.edu/~dalton/i8051/i8051syn/