What kind of app we talking? You can do a crustini cucumber combo ( or the like ). Wings are always a fan favorite ( smoked-deepfried-grilled ) with a bunch of dipping sauces.
Surprisingly, meat-cheese-cracker platters hold up well in the heat.
Chips and salsa are always good this time of year. Make your own salsa, some fresh jalapeños, red onion, sweet red pepper, fresh garlic, and tomato sauce.
Tons of options.