I added it to my Carpet cleaning several years ago. You can get more money for the same area for sure. You need to invest in the right equipment, although to start with you could just do the easier jobs like ceramic and porcellain (not textured). Work is slow to come in but I've had most work simply by telling customers while I am cleaning their carpets. I do get some work through integrating it into my website but not that many, whether a seperate site would be better I'm not sure.
Training is a necesity as these floors are expensive, so you need to know what you are doing.