We try to get a sponsor for our little school members. Everyone else pays a nominal fee (like under 2 dollars a cone) for a hand dipped cone from brewsters. Everyone enjoys it!
I should have said ours if free as well--- we hold it a week before school starts--- it's been a great way for families to catch up and the school has the classlists posted the same day so the kids get to find out whos in their class-- with adding the gymnastics areas--- it was a great way for the adults to talk while the kids watched and interacted with the gymnists.... plus we held it by our new playground so the kids also got to enjoy playing on the new pieces we added.
We do one every year at the beginning of school; no charge. It's meant to welcome everyone to another year and foster friendship between students and families. We discussed adding a performer, but decided against it as focusing on the performer doesn't necessarily encourage families to get to know one another.
We had someone from a gynmasics company come out last year and do demos-- the kids loved it and teh company even included the kids in some of their routines... we also added music during the event-- and we had sign-up sheets with events that were at the start of the year on display.
We've made postcards this year with all the PTO dates and times and we will be handing them out to everyone there and at our open house events.