I've got one for ya--my dad lived with his parents until he and my mom married (he was around 25, I think) but insisted that they live next door. He spent all his free time at his parents' house, not his own house. After he and my mom divorced, he moved
back in with his parents and stayed there until they passed away. I was in high school then.
Now he's built himself a house and is independent, thank goodness, but wow...it only took him until he was almost 50!
I lived with my parents for about a year after I graduated from undergrad because of unfortunate circumstances (e.g. health problems), but it wasn't ideal. Now that I've been living on my own for a couple years, I can't imagine going back. My friends in the U.K., on the other hand, live/lived with their folks for a long, long time after college. It's normal, from what I gather. The kids have jobs and contribute to the bills and stuff, and they pretty much come and go as they please.