Free (or really cheap) things to do in Nashville

So, my friend Katie is coming to Nashvegas in about 6 weeks, and I'm looking for some free (or really cheap) fun Nashville-y things to do. If anyone has any ideas, I would LOVE to hear them.

This is what I have so far:

Parthenon Visit-Free for the outside, and I think we'll survive missing out on the museum. It was cool, but not essential.

Stone Rivers Greenway-A trail thats really close and great for walking with a stroller, dogs, exercise etc. It should be nice, so we can always just take a relaxing walk.

Opryland Resort-The resort is expensive and lavish, as is the parking, but thank goodness there's a mall next door and we can walk. I've always wanted to explore all the gardens and such, should be fun!

Farmer's Market-I've been during the week and on the weekend. Its not super busy during the week, but fun (if we're bored).

Nashville City Walk-I JUST found this... apparently its a walking tour that you can see a lot of historic Nashville, plus the fort that's downtown, the statues, the capitol, etc. Its marked with a green stripe on the sidewalks, interesting. Plus there's a guide. I need to do this for me, ha!

Percy Priest Lake-The lake that's right down the street from us. I know that they have a bunch of hiking trails, a beach (if its warm), and stuff. We never got to explore last summer, I was hoping to some this one.

Pancake Pantry-One of the best places to eat breakfast in Nashville. Yummy pancakes and not terribly expensive. There's also another place Natalie knew of where you bake your own batter... maybe we'll give that a try.

Music-I'm sure that SOMEWHERE there will be some sort of free music, there always is. Or some kind of interesting festival.

Ok well, I'm not finding much else, but I'm not in a very creative mood today, maybe later. Let me know if anyone knows of any free... or really cheap... things to do in and around Nashville!