DescentBB

You could send them to me via PM to avoid spoiling those who don't want to be spoiled. But myself, I'd appreciate someone sending me the locations (excluding the one to the Challenge Level as I know where it's located).

Beat the mission, the last part of the credits will tell you where they are located. (or just bust open the credit file yourself using txb2txt in Hoggle.

That tells you the level, not so much the location within it.

I think I remember maybe three of them, but that still leaves quite a few behind.

Just knowing the level's enough, I'll just search the given levels for as long as it takes