My paternal grandmother is the third eldest of 14 total (including one miscarriage, and death of twin sisters shortly after birth). My paternal grandfather is the second eldest of 4, I think.
My mother is second eldest of 5. Her mother is second eldest of 5 as well.
My father is the eldest of 3. I am the eldest of 3 (including one stepsibling).
Both of my maternal aunts have 4 children each. One of my maternal uncles is in jail, but has twin daughters. The other is childless.
My paternal uncle has one child. My paternal aunt has 1 child. I have 1 child (but hope to have at least one more someday!).
I have never known of any family personally, other than my paternal grandmother, with more than 3-5 children (I believe my choir teacher as a child had 5...two were adopted).
I find the concept of extremely large families interesting/fascinating, and scary all at the same time.
There's no way I could handle it, though!
Edited to add :
I just remembered that one of my favorite bloggers has 11 children, aged mid-thirties to about 9. Her name is Heart, the blog is Women's Space/The Margins, and she freakin' rocks!!!
Edited again to add : I think this is very regional, and tied to religion as well...in my experience, the more rural/religious an area, the more children people tend to have.
We live in urban/suburban So Cal. People just don't generally have a lot of kids here.
*power and hugs and love and admiration for all mamis/papis/parents of many*