Sounds like you're more interested in gambling but like Fishhead said there are lots of nice places to visit in the Black Hills. I take it you may be driving through on your way to Vegas so the tourist sites are not as good this time of the year compared to the summer.
If anyone is ever there in the summer, take in Reptile Gardens, some old gold mine tours, cave tours, Custer State Park where buffalo roam across the highway and tons more. It's a great place to take a family and to go camping in the summer with all the gentle rolling hills and the pine trees.
It's only a couple hundred miles from Yellowstone. A lot of people take in both parks in one trip.