Where's a shovel and pail when you need 'em?

Quite often I take my kids to the park/playground and on several occationss the outing is unplanned. I just happen to drive by a park while out running errands or something.
Many kids at the park bring toys to play with the sand and they don't always like to share.
I've found it's a great idea to keep a bag of playground/beach toys in the car.
I keep an extra pail, shovel, and misc. sand toys in the trunk.

It's also a good idea to keep a minimal diaper bag in the car with wipes and diapers-then you don't have to lug around your larger diaper bag for simple errands or an afternoon at the park.