Rigs of Rods (RoR) is ideal for people who dream of taking control of big machines. It's open source and has been developed in the spare time of the developers.
Rigs of Rods is a 3D truck, car, airplane and boat simulator that offers little more than the thrill of the ride. You can drive, fly or sail in a 3D environment with no particular aim other than enjoying the scenery. The developers have put a high premium on ensuring that the feel of each vehicle is as realistic as it can be and they've done a pretty good job. I mean, it's not Grand Theft Auto in either graphics or feel but for a free simulator, it definitely offers a realistic experience.
Crashes are also realistic leaving severe damage to your 4x4, truck or whatever else you choose to drive around. The movement and control of aircraft is realistic and the bobbing and swaying of ships in the sea likewise. You can view each vehicle from almost any external angle and your dashboard is displayed along the bottom of the screen. The bonus of Rigs of Rods is that it's gained such a cult following that many users have contributed their own vehicles so if you've ever fancied driving a Ford Mustang around the desert, then here's your chance.
Rigs of Rods is not only a great name for a simulator, it's simply a lot of fun. Shame that there's not much point to it other than driving around though.