I Googled "slow cooker sausage recipes" and got several hits. I would imagine your brats (and maybe another pacakge, perhaps not spicy, depending on the number of people you're feeding) and some liquir and rice would make a nice dish. You could also slice up the sausages and sautee them with onions and peppers ahead of time and use the slow cooker to keep them warm. Maybe toss some cooked rice in to round out the dish. A gumbo or jambalaya would work as well. Here's Johsonville's slow cooker recipes: www.johnsonville.com/recipeSearch/keyword.
There's so much you can do with a slow cooker. I'd look for a slow cooker website or browse sparkrecipes with the search terms "slow cooker" or "crock pot".