Have any of you had the opportunity to see a very large pregnant belly and then later found out that the baby was quite large? Have any of you had the opposite situation where the belly was huge but then you find out that the baby wasn’t all that big? Any thoughts on correlation?

Would depend on a case-by-case basis. There are instances where a pregnant woman's belly is small at term, but the baby's large, and as you said, large bellies producing a small baby. On the former and latter, amount of amniotic fluid and a woman's size while pregnant plays a large role. 

Depends on various factors.  My wife had huge bellys, and all my kids were 7 and 8 lbs

1 woman had a 12 pound baby but she went 42 weeks. Was large well before that.

My biggest baby I was the biggest I've been out of my pregnancies, but I went over my due date. Also, I wasn't that far behind belly size wise with my second largest. I did have some extra water during that pregnancy, though. With that said, none of my babies have been above average, but I think my belly size was with two of my pregnancies.