[tptacek]

In your scheme, if your password is "apple scrapple", the hash value is always going to be (say) "f1d2d2f924e986ac86fdf7b36c94bcdf32beec15". An attacker can precompute that and just use text search to find everyone with the password "apple scrapple".

[keeperofdakeys]

They would still need a rainbow suited to the algorithm that is used to create the salt, or to have it large enough to contain the password+salt value within it. Still means that the entire database can be used with the same rainbow table, however.