@beyondcelery --thanks for sharing this idea! I didn't have all the same things as your recipe below, but I just tried it and here's what I did. They're awesome!
1.25 c steel cut oats (mine had millet and rye berries in them, too)
3/4 c flour (maybe need more, dough was too sticky to roll out)
1 c sugar
1/2 butter
2 TBS chia seeds
1 tsp vanilla
1/2 tsp gray salt
1 c. roasted, chopped almonds--as small as I could get them without working too hard!
Oven 350F.
scooped onto the cookie sheet with cookie scooper and squished to about 1/4" thick with my fingers, then 18 mins or until the get nice and brown around the edges.

Thanks to all!

Leftover Oatmeal bread
http://www.foodnetwork.com/recipes/alton-brown/leftover-oatmeal-bread-recipe/index.html

Turn it into a bread! Oatmeal bread is delicious.

Good Eats recent episodes featured a recipe very similar to this, using leftover breakfast oatmeal--though with rolled oats; I'm sure any would work.

http://www.foodnetwork.com/good-eats/oat-cuisine-ii/index.html

Mix in a bit of flour, butter, bran, and sugar, then roll out about 1/4 inch thick. Cut into squares and bake until crisp. It's one way to make traditional Scottish oatcakes. You can also form them into slightly thicker rounds and bake them till dry as well. They're great for breakfast with jam, lemon curd, or peanut butter. They keep in the fridge for 1 week easily.

Here's my mom's recipe. It doesn't use cooked oatmeal, but you can just replace the uncooked stuff and hot water with your cooked leftovers and it still works. (Use a bit less flour; use your judgement as you mix it together because you want it to be the consistency of pie crust.) They'll be different in texture, of course, but still delicious. Pecans are optional, but add a nice flavor.

Scottish Oat Cakes
¼ cup boiling water
¼ teas. baking soda
1 cup rolled oats
1 cup oat bran
1 cup flour
½ cup finely chopped pecans
½ cup sugar
½ teas salt
½ cup solid shortening
1/8 cup butter (1/4 stick)

350 degrees, 13-15 minutes

Split dough in half and roll out one at a time on a well-floured board to about 1/8 or ¼ inch thick. Cut into squares or rectangles and place on cookie sheet. Bake.

My Scottish mother would put left over oats in a pie pan to set til the next day, then slice into wedges, slowly saute in butter til both sides got a wonderful crust on them. We would have it for breakfast with maple syrup or treacle, depending what was in the pantry. Think of it as Scottish polenta.

I sometimes add it to waffle batter.

drbabs: that sounds delicious and like a good solution to my not wanting to deal with pots and pans in the morning. :)

AEC- you could use them as a binder for making veggie or bean burgers, or maybe as a risotto substitute in an arancini recipe (work some sauteed shallots and maybe mushrooms, wine, and parmesan cheese into them and then proceed w the recipe), or in a stuffing type of dish-- sounds like a yummy problem to have. ;)

How about turn them into a topping for a fruit crisp/cobbler type dish?

oh, haha. Sorry.

Thanks. To clarify, I'm looking for something interesting to do with them other than reheat next morning.

I make a large batch of steel cut oats every week. I refrigerate them and every morning I take a portion and I mix in fruit, fruit butter, honey, maple syrup, nuts or whatever I'm in the mood for and reheat them in the microwave oven. (I happen to like them dry. if you like them soupy you could add some milk, too.)