1) IPs which are new to the site must wait for a period of time, probably anywhere between one and seventy-two hours, to post. This does two things: it encourages new users to lurk moar and it prevents banned people from just resettingtheir IP and continuing to shit-post. Spammers like the pedobot on /tv/are fucked.
2) Posting on /pol/ sets off a one hour cooldown on posting on all other boards that prevents the relentless /pol/ shit-posting and racebait that most boards now suffer from.
3) Phone-posting is banned. This stops shit-posting and punishes Redditors, which most phone-posters are.