This is provided by QIT, Qatar Adventures and some others. I am not sure where their offices are located. However, one of them have an desk at the Marriott lobby. They provide, city tours, dune bashing, overnight in the desert, with varing price ranges and loads of entertainment. I had the brochure with me, dont know where i put it, sorry.

Sorry, QIT also has various names, so please check them out at the Marriott.