It might only help a bit, but many southwestern recipes for chili and soups use Masa as a thickener. Not what you want to hear in triple digit heat, but something to consider as it cools down!

Pupusas are easy to make and so delicious -- I like to think of them as the ultimate quesadilla! Just make your masa as if you were going to make tortillas, but roll them out a bit thicker, put your favorite quesadilla fillings on one tortilla, and then seal another tortilla right on top. Cook on a comal or cast-iron skillet with a little bit of olive oil or lard, if you swing that way!

http://operagirlcooks.com

Get a hamster.

How about making Gorditas? You can stuff them with this Rajas recipe. http://eat-drink-garden.com/2010/06/rajas/

tamales!

this is my favourite recipe i have found so far...i use turkey thighs/drumsticks instead of pork:

http://www.deliciousdays.com/archives/2007/03/27/grandma-salazars-tamales/

cornbread? or feed to escargot?

Hahaha! that is so much corn flour! I was going to ask the same question and I only have the typical 5lb bag!

Maybe you could use it as a building material like cement? Or maybe try for the worlds largest tortilla?

But more seriously:
I'm pretty sure corn flour is gluten free (can anyone confirm?). So perhaps you could use it to make your own gluten free flour mix? You'd probably need to add some tapioca flour and/or potato starch maybe some rice flour. Experiment and let us know how it goes!

This was a past article on King Arthur's Gluten free flour mixes ->

http://www.thekitchn.com/thekitchn/baking-products/good-news-king-arthur-flour-now-carries-glutenfree-flours-117063

You can do some beverages!

Champurrado (this one goes excellent with sweet tamales for breakfast)

http://www.gourmetsleuth.com/Recipes/Hot-Beverages-655/Mexican-Champurrado-369.aspx

or Atole

http://allrecipes.com//Recipe/mexican-atole/Detail.aspx

for the atole you can use pretty much any flavor you'd use for a milkshake (vanilla, strawberry, coconut, etc)

AND if you don't want to use it all on just food you can always make some cornflour paint

http://www.bestrecipes.com.au/recipe/Cornflour-Paint-L2121.html

You can make a corn bread with it, the corn bread will come out less grainy and coarse though.
Makes a pretty good dumpling as well.

How about donating it to a food pantry or soup kitchen and going and buying a 5 pound sack if your finances can accommodate that.

In response to caliH -

I have used this brand of corn flour in gluten-free muffins. The corn taste is not too strong, and it's much finer than cornmeal...so they don't taste too much like cornbread, especially if using some applesauce or canned pumpkin in the muffins.

This was a couple years ago before very many gluten-free flours were available in my area, so I don't remember what other flours I used with it. Probably tapioca and potato starch, and possibly a little garbanzo bean flour (having some protein improves the texture).

Use it for gluten free all purpose flour mix. See the recipe on the site below.

http://www.glutenfreecookingschool.com/archives/gluten-free-all-purpose-flour-mixes/

I made muffins with 3 parts rice flour, 3 parts masa and 1 part starch (potato or corn) with good result especially if I put a lot of chocolate chips in the batch. :)

Thickening soup/stew, making gravy, and playing tricks on people? At least, if I'm right about what this stuff is... (Very fine-ground, will dissolve in cold water, has some weird physics going on with viscosity and pressure that mean you can shake it into a fairly solid lump and then hand it to someone and have it liquefy?)

Pancakes!

I second the gorditas suggestion. Fill it with picadillo and queso fresco. Yum!

I had this same problem (although with far less masa :) ), and found this Masa Cornbread: http://www.chow.com/recipes/11286-masa-cornbread
I'd tried a straight substitution on regular cornbread recipes, but found them to be more dense than I like. This recipe however works well. A consistent variation I make is to include crushed fresh corns kernals.

One quick follow-up: the pancake idea sparked my interest, and I found these lovely-sounding recipes:
http://www.mexscape.net/Bread/Pan/masa-pancakes.html
http://www.epicurious.com/recipes/food/views/Masa-Pancakes-Topped-with-Poached-Eggs-and-Chipotle-Ranchera-Salsa-101035
I also remembered I have a recipe for Sweet Corn Pudding aka Sweet Corn Cakes, a popular if unhealthy side dish served in Mexican-inspired restaurants in California:
http://legacy.signonsandiego.com/uniontrib/20080910/news_1f10readers.html

You can make mexican corn cookies "coricos" I found this blog, but I don't use orange juice nor wheat flour, just maseca, shortening, sugar, maybe a little cinnamon and a little bit of water.

http://prietasnotes.blogspot.com/2009/02/corico-of-my-dreams.html