Not everything you do indoors has to be a game. In fact, if you have decent lighting inside, it can create a perfect scenario in which to have a photo shoot. Not only will it be a fun way to practice an art, it will help your dog develop better patience and command when you inevitably have to tell them to sit or stay, and you'll get to walk away with some visual memories as well!
While it's considerably less cleanup to groom your dog outdoors, sometimes it's just easier, more comfortable, or just plain more convenient to do so indoors. As long as you're not pulling their hair too hard or holding them down, most dogs enjoy at least some aspect of grooming, so not only is it good for their looks and health, it's another activity to help strengthen your bond.
Whether you're stuck inside due to weather, time or just because you want to be, take advantage of it by working with your dog. While they may not be excited by training itself, pleasing you, spending time with you, and getting treats are all reward enough to get what you want out of them. Work on behaviors you want to improve, especially if they're indoor specific, such as not jumping on the couch without being invited (or at all in some households) or not begging at the dinner table. It's good quality time and the means reward in the end!