When posting on a thread more than two weeks old, you should get a message saying that you should cancel the post unless you think it is relevant and the topic of the thread is still active. It should let you post it if you want to, but warn you that bringing up old threads and/or spamming can lead to a ban.
How about something that prevents you form posting in a thread that is more than 15 days old, if you want to post you will have to ask permission from a moderator?
@gamax92(View Post) Hehehehehe. @DRAGONF0RCE(View Post) Not a bad idea, if the topic is over 2 weeks old, maybe you should get a warning. And a threat of being banned. >:D