Scary numbers. Are we talking cracking a salted password hash table, Chaos? If you're saying you can pre-compute a rainbow hash table for a single salted password like "Correcthorsebatterystaple" and get a hit in a few seconds, that kind of speed would blow me away. And would make me think about taking out all of my money from the bank and burying it in a hole in the woods!

On a related tangent, if someone has access to the password hash table on some server, the user is already in deep trouble. Which is why you shouldn't make the bad guys' lives easier by reusing passwords (or usernames) for important websites/accounts. That is, a bad guy has already compromised the server for system A if they can grab the password hash table. Don't make it easier for them to get into your account on system B by using the same username/password from system A on system B.

And also why having the ability to use unique email addresses for each website is worthwhile to me. Many websites use an email address as the user account value. If a hacker can obtain the username, email address and password for me from system A, that info will not match on system B, C, D, etc.

For example, I've been a longtime Yahoo email user. The paid version allows you to create unique passwords in the form of rootword + whatever @yahoo.com. That way, you can use a unique password for each account and make life tougher for the bad guys if the email address is the username for an account.

If they can't just reuse your online poker username/password at the login screen for your bank account, then they'd have to try some other method--actually hacking into the bank's server, using a "spear phishing" attack against you, keystroke logger, etc. Except for the spear phishing attack, that's a lot more work to get at your paltry bank account balance and probably isn't going to happen. Then again, my money might already be in that hole in the woods by then!

Equally useful is that this email feature lets you more easily cutoff spammers by deactivating certain email addresses without having to totally throw away an email account and go through the trouble of changing the email address for all of your accounts. Although, I have to admit that spam filters work remarkably well nowadays, so I haven't had to deactivate an email address in quite a long time.