Thanks for the link, though that one is not even pipelined!
It has been used for teaching cpu design for 15 odd years AFAIK, and for something that firmly embedded in academia one would expect to see a pletora of papers and student works that add features to the basic design.
I have been toying with making two additional instruction types for the architecture, but that is of course miles and miles away from something synthesizable... (hence my interest in something that already works to see if it can be crafted on to it if I can teach myself enough VHDL)
EDIT: And Wikipedia is as usual a great source of information
http://en.wikipedia.org/wiki/DLX