Cacao nibs are crushed seeds from the Cacao plant. It is these seeds that are the key ingredient in chocolate. While not technically chocolate themselves, our nibs do have a wonderful coco smell to them, and will provide a very subdued coco-like flavor to any beer.
A few of us at the shop began to use these nibs like you would a dry hop, but in a process we coined - just to sound official - called "Dry Nibbing". All it means is simply adding the nibs to your secondary fermenter or keg for a couple of weeks (4 ounces per 5 gallons is a great place to start), allowing the beer to draw out the subtle flavors and aromas of the cacao nibs. We have had great success with leaving the nibs inside the keg for as long as 8 months! They can also be used in the boil or mash - wherever you would like to experiment with them. Any addition of the nibs pre-boil will impart some bitterness, so use a lot less than you would when adding them to a keg. (Recently, our friends at Stone Brewing Company made a stout using cacao nibs in the boil to actually replace some of the hops in the recipe!)
Our cacao nibs go great with darker beers like porters and stouts, but could blend with any beer - perhaps a wit or a saison!