There are a handful of boards that will work as a replacement, though most are getting up there in age at this point. I was able to find a stash of Asus A7N8X-VM boards locally, and the -LA version works too. The Intel D945GCLF2D, D945GCLF2, D945GCLF might be the newest option available.
The A7N8X-VM requires a slight modification to the northbridge heat sink. I need to cut off a couple of fins to fit in the IO board.
There's plenty of posts on all these boards that really helped me out.