I think I already mentioned Shakespeare by the Sea, but there are free Shakespeare performances in Griffith Park, as well. This year, they're staging "Much Ado About Nothing" and "Romeo & Juliet." To find out more, click here.
And yesterday, when I mentioned purchases, I forgot one: my kids love ping-pong, but we don't have room in our house for a dedicated table. I bought one of those adapter sets that transforms a regular table into one suitable for ping pong. (It's called "table tennis" for a reason.) If you've got a kid who loves table tennis, it's not expensive to buy the kit; brands I saw available online varied between $15-$40.