Verily Serif Mono is derived from Bitstream Vera Serif with the same proportions as Bitstream Vera Sans Mono. Only the primary ASCII characters have been modified; I have no plans at the moment to modify the extended character set or to do a bold version.
Verily Serif Mono is released under the Vera license, with the exception that the name does not need to be changed from "Verily." Verily is so named since I have seen many posts asking whether a Bitstream Vera Serif Mono font exists; verily, it does now. Download Verily Serif Mono in OpenType format, along with the FontForge source file and auxiliary files. (The download is a gzip'ed tar file (.tgz) since GeoCities does not allow arbitrary file types.)