On a whim, a friend and I made brownies last night, and since I only had enough chocolate and eggs for a half batch we decided to experiment by carmelizing the butter & sugar before adding chocolate and eggs.
The carmelized sugar crystalized a bit as I cooled it down and added chocolate, but that wasn't a problem considering many people add nuts to brownies for texture.
Next time, I'll probably carmelize half the sugar in the butter, cool it in an ice bath a bit, add the rest of the sugar, cool until the chocolate won't burn, then add the chocolate and finally the eggs. I would also have a candy thermometer handy to keep better tabs on the carmelization, but we were impatient and had already thrown caution to the wind so we just winged it. If you don't have a thermometer, turn the heat down a bit as it looks like the sugar is just starting to melt so it heats evenly and doesn't get away from you; the transition from sugar granules to melted sugar to burned sugar happens pretty quickly. Having a larger pot at hand with water and ice in it so we could rapidly cool down the carmelized mixture worked well for us.