[Neuro Toxin]

You can use a steamid.

Edit:

I'll mention that InsertPlayerCookie and GetCookieByPlayerId are functions that store/retreive playerid to cookie via mysql

[Puppetmaster]

You could probably get high quality fingerprints with PHP if you really tried ;)
It might even be possible to get around reinstalls of steam with a little effort :O

[DJPlaya]

Originally Posted by Neuro Toxin Smurf joins. Tracking cookie is found. If banned disconnect them.

I LUV it, I will create a Pull Request to the SB++ SourceSleuth