CouchDB passwords are stored in a salted, hashed format of a 128-bit salt combined with the password under SHA-1. This method thwarts rainbow table attacks, but is utterly ineffective against any dictionary attacks as computing SHA-1 is very fast indeed.
If passwords are to be stored in a non-plaintext equivalent format, the hash function needs to be a "slow" hash function. Suitable candidates for this could be bcrypt, scrypt and PBKDF2. Of the choices, only PBKDF2 is really widely used, standardized and goverment approved. (Note: don't be fooled that the PBKDF2 is a "key derivation" function - in this case, it is exactly the same thing as a slow password hash.)