Cold pasta salads are great for the summer, I love to use rice shaped Orzo and you can add just about anything. I prefer to throw in roasted red peppers, red onions, fresh green, red, orange, or yellow bell peppers, tomatoes, sun dried tomatoes, pancetta (cooked) or salami, grilled chicken, roasted garlic, or roasted eggplant. Fresh herbs add a great flavour, I use fresh basil, mint, and thyme. And tossing it all in olive oil and lemon juice works great. Or you can use other combinations like oil and vinegar.
Also, Gazpacho (a cold soup) is great for hot days, it is Spanish rather than Italian, but I don't feel that it strays far from Italian cuisine.
Melon and prosciutto crostini for appetizers.