Ascelpias Tuberosa, Butterfly Weed.
Echinacea 'Sombrero', hosting a black butterfly.
Tickseed (Coreopsis) "Route 66", a lover of heat and sun.
Bear's Breeches (Acanthus mollis) likes partial sun, and I think prefers a slightly alkaline soil and decent drainage.
Echinacea, as most of us know by now, includes the native Echinaceas purpurea and tennesseensis - the purple coneflowers, and slew of cultivars of crazy bright colors in the white/yellow/orange/red ranges. They grow in full hot sun, don't want extra water, and have not too many problems. The natives grow about 3 feet tall, the cultivars come in all sizes.
Butterfly Weed, part of the milkweed genus, is both a wild and cultivated sun-lover. Best in full-sun, not excess water. It grows about 18 inches high and blooms mid/late summer with a bright orange clusters. It doesnt transplant well but I have saved the seed and started plants. Be patient in the spring as it really waits for very warm weather before emerging from the ground. I leave a marker at its home spot in my garden so I know where it will be each year. There are cultivars to be obtained as well, but I like the native so much, it's all I want.
Coreopsis is a great sun-lover that is pretty easy care. It doesn't need a lot of water,and blooms most of the summer. Sometimes they can get a little floppy, so may need staking or some friends nearby to crowd them into standing up. They are daisy-like blooms with the cultivars available in yellows, reds, whites and oranges. A fantastic starter is "Jethro Tull" with its appealing cupped bright orange petals.
None of these get supplemental watering in my yard, unless we go through a two or three week drought.