650+ spam blogs in less than 12 hours - MySQL full/Site down

Hi!

My multisite network bloggerspoint.dk has received over 650 spam blogs sign ups in the last 24 hours, and my VPS couldn't handle it, and MySQL is now full.

has anyone any idea of what I should do? If i try to start MySQL from SSH, i get this message: "ERROR: The partition with /var/lib/mysql is too full!"

As the site is down, I can't get in and delete all the spam blogs.