A ping list is just a list of names of Freepers who have an interest on a given subject. If I hear anything new about Terri, and your on my list, it means I'll notify you in your comments section. Then you can check out that thread. Sometimes it's the same thread but with updated info.
The thread is a HUUUUGE one, over 5000 posts! I can't remember exactly where within that thread it came up, but I'm gonna guess that it was somewhere between posts 700-2000. A lot of material was covered. I remember staying up late for weeks on end when I first found this thread. It was the first I'd heard of Terri. Don't be intimidated by it! Just take it in chunks and keep track of how far you've gotten in a little notebook or something. Takes notes and copy and paste to wordpad for easy reference. Good luck! Let me know if you find out anything that you think is really important. It could be that something was overlooked, and you've got the eyes with which to "see" it.
I call it the first monster Terri thread, cause there was another soon after that made it to like 2000+ posts.
http://www.freerepublic.com/focus/f-news/971896/posts