Hi, BML. If the roast is already sliced in the gravy, you could serve it over some noodles or rice and make another meal out of it. I love that for an easy leftovers dinner - a couple grinds of black pepper and I'm good with that.
If it's just the beef alone, like Beth mentioned, soup and/or sandwiches. Tacos are pretty good too, with a good sprinkle of cumin or chili powder.