Plant quick-maturing leaf lettuces under pole bean teepees to provide some shade. The bean foliage will shade some of the sun and keep the plants and soil cool. Plant the beans early.
Plant some lettuce or spinach between your corn rows, or on the shady side of a row of tomatoes.
Try multi-planting. Plant lettuce, carrots and onions within the same wide row (15 to 16 inches across). Harvest the lettuce when young, leaving expansion room for carrots and onions. You can mix and match with other crops, too, including beets and spinach.
Save a window box for a peppery, green-like curly cress. Plant lettuce in a small section of your flower garden, or use it as a decorative, edible border. The foliage is lovely and contrasts beautifully with flowers.
Succession plant short rows of lettuce to avoid having too much mature at once.