I have some muffin recipes that call for buttermilk.

Also, an opened or unopened container of buttermilk stays good just about forever. Since its cultured, like yogurt, its not very receptive to having bad stuff grow in it.

Op here. Thanks for all the ideas -- they look wonderful -- bye bye buttermilk!

Someone mentioned buttermilk chicken, which I'd vote for. In the past, I have gone to Ina Garten's recipe: http://www.foodnetwork.com/recipes/ina-garten/oven-fried-chicken-recipe/index.html

Incidentally, her chocolate cake also calls for buttermilk, and I highly recommend it - just be prepared for a decadent treat: http://www.foodnetwork.com/recipes/ina-garten/beattys-chocolate-cake-recipe/index.html

I use buttermilk in a sort of ranch salad dressing for cole slaw. I think its buttermilk, vinegar, dill, garlic, salt and pepper - ends up much less sludgy than mayo-based dressings.

Smitten Kitchen's buttermilk roast chicken inspired by a Nigella recipe:

http://smittenkitchen.com/2012/01/buttermilk-roast-chicken/

We have this almost weekly with roast vegetables.

Mashed potatoes

Google buttermilk pie (a kind of chess pie)

Google recipes that involve buttermilk marinade -- chicken is great marinated in buttermilk overnight.

I can't vouch for this since I'm going to try it for the first time this week, but it calls for buttermilk: http://www.ezrapoundcake.com/archives/12345

Summer corn cakes

biscuits and cornbread

buttermilk biscuits are very easy and freeze-able. I just roll, cut, and place on a baking sheet in the freezer.
This cake:
http://smittenkitchen.com/2009/05/raspberry-buttermilk-cake/
is fabulous and easily adaptable to whatever you have hanging around.
Last resort, we make more waffles or pancakes and freeze them. Waffles toast up nicely in the toaster!

I make this all the time and really like it:
http://www.food.com/recipe/buttermilk-brined-pork-chops-141380

I also make this salad quite often and the buttermilk is used in the dressing (it sounds gross but is really good. Frankly, I don't know what posessed me to even try it but it is one of our go-to dinner salads):
http://www.marthastewart.com/342084/chopped-salad-with-spicy-pork-and-butter

I live abroad and can not find buttermilk here. I now make my own for all recipes calling for buttermilk and don't notice any difference in the finished product. I cook and bake A LOT!
I do 1 cup milk plus 1/2 TB lemon juice and 1/2 TB vinegar stir and let rest for 5 minutes or so.

I used to buy fresh buttermilk for pancakes too but I never used the whole container and it always went to waste. I know it's not quite as good as fresh, but I found the next best thing was to buy powdered buttermilk for these recipes or to make my own substitute by adding 2 TBSPNs lemon juice to every 1 cup of milk.

That said you might consider smoothies with buttermilk or substituting buttermilk for milk, yogurt or cream in baked goods recipes.

Hope this helps.

I buy buttermilk these days to make pancakes every week. Any other good recipes that use buttermilk?