Being the obnoxiously useful little tofu I am, I've been reading around the Plan Your Own Adventure forum for a while doing what I can to help people find other people looking for rooms, rides, etc. to lighten the cost of coming to the con for those who need it. I was just doing that, and I thought "man, this would be a lot easier if these threads were stickied".
So, here's my thoughts: ask folks to tag their threads with a lamp icon, signifying they wish to have moderator review. Set requirements for what a thread needs to look like to get stickied in there, put up an Announcement post there so people will be able to read these guidelines, and go at it. I think that most people would agree that carpool and roomshare threads are more important that threads seeing who wants to go hang out at the mall some time.
This is just a thought; feel welcome to build on this and let us know what you would think.
It should also be mentioned that there is a search function for this forum, so if someone is looking for a hotel room, they could also use that to search for an existing thread before reserving their own room and trying to fill it.