I always use virtual tours on my listings, it is a wonderful way to market a property and get buyers to spend more time viewing your listings. It helps sell the property. Unfortunately not many realtors use virtual tours, and many more don't even put any photos on mls.
I would say that about half of the agents use them. Aside from virtual tours there are programs or options such as Point2NLS and Single Property Sites that allow you to create an advanced, professional looking slideshow, but not necessarily a virtual tour. The best virtual tours are the 360 degree tours. They allow you to see every nook and cranny!