I bought buttermilk for a specific recipe, but now I have some left and have no clue what to make with it...any ideas?

Buttermilk pancakes comes to mind

Biscuits, use in mashed potatoes, baking, soak chicken before breading......

Biscuits and pancakes are both great ways to use it. Someone also posted a nutmeg donut muffin recipe that uses buttermilk too .

If you choose to fry (or oven fry) foods, you can use it as a binder for the breading, rather than egg wash.

I was just watching an episode of Everyday Italian where she made fried ravioli by dipping ravioli (premade, from the refrigerated section) into buttermilk and then breadcrumbs and frying. It looked so good!