I'm not a huge fan of temps that are LOW in the high seventies. Thankfully i live in a house with central air conditioning and can get my gardening done early in the morning.
The garden is not so lucky. I'd love to invest in some shade cloth for the mid Summer season, but instead i allow my veggies to peter out some during this hot weather and wait for the shorter days and increased production of the Fall. My cukes are sad and withery, but they gave me plenty of goodies earlier in the season. The tomatoes have been hacked back and new transplants set into the ground - all are doing well and reinvigorating themselves nicely. The peppers are loving this oppressive heat: i allow them to get sad and wilty in the hot sun, to perk back up on their own in the morning. If you over water your peppers, they'll succumb to wilt and their fruits won't be as spicy.
Please remember - if you are watering your garden during these hot Summer spells - water in the morning!
Stay cool out there!