http://crackstation.net/hashing-security.htm
Salting inherently makes your user’s passwords better automatically by prepending or appending a random string. So lookup tables become useless.
But if the password hash and salt table is compromised then salt will not help (as in LinkedIn case). LinkedIn should have been using bcrypt, which is an adaptive hash that would have slowed the brute force time down to the order of 10s of hashes per second.