When using md5();
to store passwords on a table in your mysql database.
keep in mind the same proccess will be required when checking the entered password from the login form, aganst the one in the database.
Another example of a hash generating function is
sha1();
u could always wrap the 2 functions and create a simple hash generation method
$string = md5(sha1($string));
return $string;
// RETURNED HASHED VALUE
It is also possible to use the salt() function, which allows your own "public key" to an extent.
salt("mystring123", "jz");