Gravitational time dilation may have some useful applications. The closer you are to the black hole, the stronger you experience its gravity, and stronger gravity means you experience less time than people further away from the black hole. Of course, all gravitational masses cause time dilation, but black holes are especially small compared to other equivalent masses, so you can get much closer to them, and so the amount of time dilation can be much greater.
For example, if you have things which are used very rarely but require expensive ongoing maintenance - e.g. nuclear weapons - then you can put them near a black hole, and they will degrade slower relative to your frame of reference. That means lower maintenance costs.
You might also have some group of people who want to permanently live close to the black hole, so that they experience time slower and are able to benefit from a faster rate of technological progress from the outside world. This would mainly be people rich enough that they don't have to work to earn a living (as time dilation would proportionally reduce the value of their labour to people away from the black hole), but perhaps also include people with uncurable diseases who want to survive "longer" for a cure to be found.