Daylily
Iris
Huechera
Tiarella
Lilium
Canna

I could go on and on...

UT Gardens publishes a list every year of what does well here.
http://utgardens.tennessee.edu/tips.html
Scroll down to the "best and the beautiful" by year. Perinnials are in the middle of each year's page.
Or just go to the gardens -- they're free -- and wander around. When you see something you like, look for the name.
The UT Gardens are trial gardens. They test to see what works well here and what doesn't and publish the results every year.
They're an incredible resource.
That same link also gives you month-by-month gardening advice.

Here is a link that might be useful: UT Gardens Tips and reports

You'll find more detailed trial data for perinnials at the link below.
BloomsDay at the Gardens, with workshops, will be coming up June 27-28. Look for workshops on good plants to grow. They are usually excellent and included in the price of admission.

Here is a link that might be useful: UT Gardens Trial Data

I didn't know about that UT link! Cool!

You need to get yourself a good perennial encyclopedia! :) Then look for stuff that is hardy to Zone 6 or 7.

When I first started gardening I ordered some of the Time/Life series of gardening. I still have those books - they are great reference. I also really like Reader's Digest gardening books.

I rotate out my collection and read a few at a time in short spurts. There is one I found a couple of years ago on sale at Borders for $5...it's encyclopedia sized, by Reader's Digest, and I think the name is something like "200 of the Hardiest Plants"...or something like that (it's downstairs and I'm too tired to go down there. LOL) Anyway, it's a great one. It lists the top cultivars for performance as well, which is neat.

Here are a few more for sun:
Alstroemeria
Balloon Flower
Hollyhock
Stokesia
Gladiolus
Crocosmia
For shadier spots:
Columbine (short-lived but self sows reliably)
Hardy Begonia (Begonia Evansiana) - invasive in deep shade.
Bleeding Heart