perlfunc recommends a random salt:

crypt PLAINTEXT,SALT
...
When choosing a new salt create a random
two character string whose characters come
from the set "[./0-9A-Za-z]"
(like "join '', ('.', '/', 0..9, 'A'..'Z', 'a'..'z')[rand 64, rand 64]
+").
...
[download]

The random salt makes the cracker's job a lot more difficult.

conv