In the course of thinking about
this, google led me to
this amazing post by Jarcho from 2012 that I really, really wish I'd seen back in 2012. It fully documents the binary file formats for .bindat and .raw and comes pretty darn close to fully documenting binlayout, .pak, and .mod. I think it's worthy of a spot in the wiki.
I'll add it right away, I'll just copy-paste it (with the corresponding "code" editing), so if someone want to add something specific later feel free to do it.
It's kind of lonely in the wiki
It's kind of lonely in the wiki 
I know, sorry! I said I'd do more for the wiki, but haven't done a thing yet.
@Chthon thanks so much for that find!
Well, already added.
File FormatsChthon if you could add some description or anything to that would be great... Since I have no real clue what I just added

I know, sorry! I said I'd do more for the wiki, but haven't done a thing yet.
Don't worry Phan, I actually think we need more people around, instead of us doing all, but recruiting people is not easy