You need not create a entirely new post but even comments on blogs or forums actually make a big difference.
Another way is to dig up old threads that were popular. When the from page stops moving and the forums/blogs are not all that interesting find a old one and comment on it. It will boost it back to the top and users will start commenting or possibly even inspire them to make a similar one.
Just saying . It works. We have done it I think twice. Shit even embedding a youtube video in the forums then talk about it a little bit. If half a dozen of us do this you will notice the difference.
I will be one of the ones doing this as soon as I get a fucking day off of work...lol.