Clifford Wolf wrote VHDL to implement a custom processor which executes the Brainf*ck programming language using a Spartan 2 FPGA chip. You can download the VHDL source and test cases from Clifford’s Homepage. Nutty stuff.

Addendum: I wrote a .signature program that implements a Brainf*ck to C compiler which is archived here. Search for “VandeWettering”.