Larian confirmed that we'd get a "home" in the underworld or whatever they're calling it.
I think it'd be great to have a trophy collection, especially for competitive victories. Eg, if you complete a romance (which only one player can complete per romantic interest), the romantic interest gives you a unique gift that you can add to your collection.
If you kill the guy someone else needed for their quest, you could also get some kind of gift or trophy you could include in your home. It's there for you to rub in the face of your co-op partner. XD