You don’t want to go overboard – spontaneity is part of what makes get-togethers fun – but you do want to have some sort of structure as far as the evening’s activities go, especially where the kids are concerned. Some fun ideas for block party activities:
Watermelon eating contest (try it with no hands!).
Making pictures with sidewalk chalk.
Water activities: sprinklers or water balloons, for example.
Visits from firefighters or police, with tours of the fire truck or police car. Just call the local stations to arrange this.
Face painting.
Hula-hoop or limbo contests.
Entertainment by a “house band” made up of neighborhood musicians, or just music performed by individuals.