My site was just hacked. No damage was done (that I could find).
Someone created an account on my forum that had Administrator rights. It was not set as active, however.
I'm guess that they created an account with a fake e-mail address, then cracked my password and made themselves an administrator? 
That's the only thing I can guess.
I've changed my passwords to something much harder to crack.
It might be one of my students. I teach a Cisco networking class and I know some of them have access to password cracking programs. But it could be someone else.
If they never posted, is their a way to track the IP address they used when creating the account?