Script I wrote quite some time ago as a response to the 'impaired' functionality of PB's minguidage feature. Had some interest in it recently so finally whapped it on the wiki.
Original waffle posted on PBBans forums.
2) **New Guid To Server checking**
This was perhaps the most effective measure despite its simplicity. ETPro guids are unreliable, and pbguids for ET are but a console command away, plus the minguidage functionality has long been broken. I created a script that collected and stored a list of pbguids of all players that connected to the server. If a player connected and his pbguid was already on the list, he could join a team and play immediately. If not, his guid was added to the list but the player was forced to sit in spectator mode for a time before he could join a team (I used 2 minutes). What this amounts to is essentially a kick-time that cannot be bypassed. A kicked player (who generates a new guid to get around the kick) can connect again but is disallowed from joining a team. Relatively few would see out their time and most would mooch off pretty quick (probably to try another server).