There were a number of them.  As others have meantioned, the TGV folks did one, there were a number of tools from DECUS, and even DEC actually released more and more UNIX into VMS themselves.   I used to carry a mag tape with vi, the shell and few basic tools that allowed me to edit things on VMS if I had to deal with it.  The biggest issue was TCP/IP, since DECnet was the only networking for a such a long time from DEC.

Stan Smith and I wrote the original VAX IP/TCP support for Tektronix in 1979, in BLISS and some small amount of VAX assembler.  My friends (former coworkers) @ CMU took this back in and enhanced it (the CMU folks did a huge amount of work on the mail interface).  IIRC I sent the tape to Danny Klein, but it might have been someone else.

I have the code from the CMU's update of our work on 9-track tape, but I think it eventually also may have gone out on a DECUS tape.    But I do know that this code base would make its way to DEC, where CJ and Wayne would take it to become the code base that started OpenVMS's version [CJ once told me he was impressed at how little they had to rewrite it, mostly removing some Vaxism's - Stan and I were not worried about portability, we just wanted something to talk correctly to the UNIX V7 TCP from 3COM (UNET) and the TCP we had written from the Cyber NOS]. 

Clem