Suggestion box

This is to all the moms (and kids and former kids) out there on what to do with spring break time? We're planning a few adventures this week to places like museums/science centers/etc., but what do you do on a day like today with thunderstorms outside and no planned activities? The kids can only play with their toys and look at their books for so long (i.e. before they start hounding me...)

If anyone has a great suggestion on something unique and fun to do, let me know. I'd love to hear it!