Depends upon how casual you want the meal.. and if you want hot or cold sides. I like cole slaw and Maque Choux http://www.food52.com/recipes/6300_maque_choux (the photo here shows shrimp, but I NEVER make it that way. It's always a side dish.

corn salad (http://www.food52.com/recipes/224_amagansett_corn_salad or http://www.food52.com/recipes/12928_dilled_crunchy_sweetcorn_salad_with_buttermilk_dressing), a simple slaw, a tomato salad (http://www.food52.com/recipes/13987_sicilian_tomato_salad_with_pecorino_vinaigrette) endless possibilities - just think summer produce and you can't go wrong.