I add a little brown sugar, allspice, ground ginger, and ground cloves to chili. I settled on this combination when I was searching for that something extra to make a good chili into a great chili. I googled and read chili recipes until I found this, tried it and loved the results. The only time it wasn't quite up to par, I had added a little too much brown sugar. Still really good, but now I know to only put about a tablespoon in it.
If you can't see the bright side of life, polish the dull side.