Also not a recipe but my secret ingredient -- add torn up soft corn tortillas in the last 30 mins of cooking. They'll break down. Some folks use cornmeal, but I like the masa taste of the tortillas and it gives a great, rich consistency.

I like to just add one or two new things to my usual chili recipe (which is less a recipe and more a random process). I've had good luck adding a few different ingredients - bratwurst, beer, a pinch of cinnamon, lamb, a ham hock. Obviously don't add all of these to the same recipe, but I've had good results with each one.

This isn't a recipe, just a secret ingredient. 1/2 to 1 full cup of strong black coffee. It works like anchovies in that it creates a mysterious but unrecognizable bottom flavor. I first discovered it through making red beans and rice. But it works well with almost any dish using beans. Even if your chili doesn't include beans it should still elevate the flavor.

This is different. And it is crazy rich so might get attention. I liked it the next day wrapped burrito style in a flour tortilla. It isn't 'pretty' so the cilantro and salsa garnish may be important. I would like it with a bit more heat, likely some roast chopped jalapenos added.
http://www.epicurious.com/recipes/food/views/White-Chicken-Chili-11452

**of veggies

My sister and I make an addictive chili with quinoa and chipotle. We use big chinks o vegoes (carrot, parsnip, sweet potato...), than add chopped chipotle in adobo or dried & ground chipotle powder. Add quinoa with the liquid--it will cook while the chili simmers.

You can glean some ideas from this website about past chili winners, I have found some real neat tips on making some great chili here:

http://www.chili.org/recipes.html