Brown sugar is a great addition to many different brews. It works great in brown ales and porters, even some Stouts. It will add alcohol and some flavor to these styles.Brown sugar can even be added to hard cider and tropical fruit wine prior to fermentation.
Brown sugar has a PPG of 45, so every 1 lb added to a 5 gallon batch will raise the gravity by 0.009. Adding 1/2 to 1 lb. of brown sugar to a 5 gallon batch is a relatively safe amount to add.
When homebrewing, you add the brown sugar at the same time as the malt extract.