Just a quick suggestion: How about only letting a user post once in the roll call forum? This idea came to me while looking at p4u1b's three posts, which were all in roll call and were all basically exploiting the concept of the forum to give this user free advertisements. Limiting the roll call forum to a single post could help deter malicious users from doing this.
N.B. This was suggested many months ago by Negative, however it was in amongst several other roll call peculiarities which were specific only to him. I have a feeling that this suggestion, along with his others, was dismissed as being due to his status as a moderator e.g. his ability to reply to his own roll call (feel free to correct me - the thread is here).