I have seen many posts on several of the forums I frequent that traffic in the month of December is as much as 50% down. Obviously this depends on the niche you are in. I have also seen a decrease in traffic on some of my forums by as much as 20%. I am rather used to this however and know that come January those sites currently in a holiday slump will grow to knew heights beginning in 2006.
The best thing to do during a slow time of the year with your forum is to continue doing the same thing you have been doing as a dedicated owner/administrator. That’s all! Don’t panic or get depressed, it is the holidays after all. 
Keep working to get solid link exchanges, keep writing/creating new content, keep pushing for viral marketing, keep on!
This post is exactly what I needed to see. I was just at the admin zone checking to see if others had the same thing going on, saw your ad there and found out that it’s perfectly normal for a holiday slump. I just started my board in November and was starting to wonder what I was doing wrong. Thanks for this tidbit of forum owner knowledge.
Yes, very typical forum behavior…at least from my experience. I am looking forward to January!