Someone over at Amiga.org
_claims_ to have recreated in HDL (Hardware description Language) some of the functionality of the Amiga OCS chipset.
Enough to get some games & Demo's to work.
Here are some pictures
of his devkit.
Interestingly he quotes that his source of knowledge on the Amiga chipset was (amongst other things) was the UAE source code.
I'd really like to see this project go opensource, I (as a HDL engineer) could devote some time to it.