I heard a term for this once and I'm not sure if I remember it right. I couldn't find anything about it but I'll give it a shot.....
"Necroposter", someone who brings old dead threads back to life. This has been happening a lot lately and I think it's due to the "similar thread" section at the bottom of the page of each thread. Most of these threads had run their course at one time, but with the amount of newer people to the board, it's virtually impossible to stop it. To some, it upsets them to see a post so old revived, to others, it's their thing they like to do in forums (Never could understand those weirdos), with the "similar threads" section, someone will post to something that's been dead for years.

Regardless, my personal thoughts on the "similar thread" section is that it's bad for the forum. If someone is interested enough in something similar, they'll do a search and come up with plenty of hits within the forum.