The crypt() function on *nix systems takes two parameters, the word to encrypt and a two-byte salt, and returns an encrypted string. The function traditionally uses the DES algorithm, which is perturbed one of 4096 ways based on the salt. The MD5 crypt was designed for FreeBSD because of export restrictions on encryption software and to allow for longer passwords. The actual salt you provide it has no effect on the actual hash the MD5 part generates (according to the above page); apparently it''s just concatenated into the result. In any case, MD5 is a standard algorithm; the "UNIX MD5 crypt" refers the the UNIX crypt() function (or crypt executable) that''s built to use MD5 rather than DES.
"I contend that we are both atheists. I just believe in one fewer god than you do. When you understand why you dismiss all the other possible gods, you will understand why I dismiss yours." - - Stephen Roberts