One thing I love in a good chili is cubed/chopped steak. The last chili I made was with a small amount of ground beef and ground pork and a london broil seared rare, then chopped into 1/2" pieces into the chili. It was awesome. I also cook my chili with beer and let the whole thing simmer for a good 8 hours. When serving I top with fresh scallions, cheddar or pepper jack, cilantro.
The dark chocolate thing sounds interesting, but I don't like chocolate/cacao with meat, although steak and duck can go with chocolate fairly well at times. Also I find stouts are too bitter in chili unless your chili has a very high fat content. I like to use a porter or ale. That's the great thing about making chili though. It's a mish mosh of whatever you want.