Make Your Own Curved Track Dolly
Putting a camera on a curved dolly can add production value to a low-budget video. It's easy and inexpensive to build one. (Link to 13 minute YouTube video)
If the curvature is a section of a circle, and the camera is pointed toward an object placed on the center of a circle, that object will stay in the center of frame.
The movement of the camera is controlled with a geared down Lego motor. This one travels about one foot every 15 minutes, or about an inch minute.
The cart is also made from Lego. I remove the tires from normal wheels and run the cart on the rims. The track is made from flexible Pex pipe, which you can get from the hardware store.